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Rapid Screening (rapid + screening)
Selected AbstractsA Microfluidic Approach to the Rapid Screening of Palladium-Catalysed Aminocarbonylation ReactionsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 18 2009Philip Abstract The evaluation and selection of the most appropriate catalyst for a chemical transformation is an important process in many areas of synthetic chemistry. Conventional catalyst screening involving batch reactor systems can be both time-consuming and expensive, resulting in a large number of individual chemical reactions. Continuous flow microfluidic reactors are increasingly viewed as a powerful alternative format for reacting and processing larger numbers of small-scale reactions in a rapid, more controlled and safer fashion. In this study we demonstrate the use of a planar glass microfluidic reactor for performing the three-component palladium-catalysed aminocarbonylation reaction of iodobenzene, benzylamine and carbon monoxide to form N -benzylbenzamide, and screen a series of palladium catalysts over a range of temperatures. N -Benzylbenzamide product yields for this reaction were found to be highly dependent on the nature of the catalyst and reaction temperature. The majority of catalysts gave good to high yields under typical flow conditions at high temperatures (150,°C), however the palladium(II) chloride-Xantphos complex [PdCl2(Xantphos)] proved to be far superior as a catalyst at lower temperatures (75,120,°C). The utilised method was found to be an efficent and reliable way for screening a large number of palladium-catalysed carbonylation reactions and may prove useful in screening other gas/liquid phase reactions. [source] Rapid Screening of New Polymer-Supported Palladium (II) Bis(3,4,5,6-tetrahydropyrimidin-2-ylidenes),MACROMOLECULAR RAPID COMMUNICATIONS, Issue 1 2004Monika Mayr Abstract Summary: The synthesis of two 1,3-diaryl-3,4,5,6-tetrahydropyrimidin-2-ylidene-based N -heterocyclic carbene- (NHC) derived palladium complexes, Pd(5-hydroxy-1,3-bis-(2,4,6-trimethylphenyl)-3,4,5,6-tetrahydropyrimidin-2-ylidene) (Ag2Br2Cl4) (10) and Pd(5-(bicyclo[2.2.1]hept-5-ene-2-carbonyloxy)-1,3-bis-(2,4,6-trimethylphenyl)-3,4,5,6-tetrahydropyrimidin-2-ylidene) (Ag2Br2Cl4) (11) is described. 10 was supported on a PS-DVB and a Wang resin, respectively, to yield catalysts 12 and 13, while 11 was used for the synthesis of a ring-opening metathesis precipitation polymerization-derived support 14. All supports were tested for their activity in Heck-type reactions using a combinatorial approach. Structure of polymer supported Pd-catalysts. [source] Rapid Screening of Lectins for Multivalency Effects with a Glycodendrimer MicroarrayCHEMBIOCHEM, Issue 13 2010Núria Parera Pera Dr. Abstract Multivalency is an important phenomenon in protein,carbohydrate interactions. In order to evaluate glycodendrimers as multivalent inhibitors of carbohydrate binding proteins, we displayed them on a microarray surface. Valencies were varied from 1 to 8, and corrections were made for the valencies so that all surfaces contained the same amount of the sugar ligand. Five different carbohydrates were attached to the dendrimers. A series of fluorescent lectins was evaluated, and for each of them a binding profile was obtained from a single experiment showing both the specificity of the lectin for a certain sugar and whether it prefers multivalent ligands or not. Very distinct binding patterns were seen for the various lectins. The results were rationalized with respect to the interbinding distances of the lectins. [source] Rapid screening in cervical cytology , a simple method with a big impactCYTOPATHOLOGY, Issue 3 2004Chris Faraker No abstract is available for this article. [source] Rapid screening in cervical cytology , a simple method with a big impactCYTOPATHOLOGY, Issue 2 2004Paul Cross No abstract is available for this article. [source] Diagnosis, clinical features and molecular assessment of the dysfibrinogenaemiasHAEMOPHILIA, Issue 5 2008M. HILL Summary., Hereditary dysfibrinogenaemia is characterized by the presence of functionally abnormal plasma fibrinogen. Dysfibrinogenaemia is a heterogeneous disorder associated with different mutations throughout the three genes that code for the fibrinogen sub-units, affecting many different aspects of fibrinogen/fibrin activity. Dysfibrinogenaemia may be discovered during the investigation of individuals who present with bleeding or thombosis, or may be found in individuals during routine coagulation screening. More specialized coagulation tests may confirm the diagnosis of dysfibrinogenaemia but do not reliably distinguish between the different fibrinogen variants and are not usually useful in predicting bleeding or thrombotic risk. Advances in molecular diagnostics have facilitated the investigation of the molecular causes of fibrinogen disorders. Several ,hot spot' areas have been identified where mutations causing a high proportion of cases of dysfibrinogenaemia are found (A,Arg16 and ,Arg275). Molecular diagnostics have also shown that many fibrinogen variants share the same causative mutation. There is a discrepancy between the quality of the molecular and functional data available for each mutation and the clinical information on individuals and their family members. However, there are accumulating data that the ,hot spot' mutations accounting for 60,80% of cases of dysfibringenaemia are not associated with a significant bleeding or thrombosis in the absence of other risk factors. Rapid screening for these mutations may provide reassurance for patients in the presurgical setting. [source] Rapid screening assay of congenital adrenal hyperplasia by measuring 17,-hydroxyprogesterone with high-performance liquid chromatography/electrospray ionization tandem mass spectrometry from dried blood spotsJOURNAL OF CLINICAL LABORATORY ANALYSIS, Issue 1 2002Chien-Chen Lai Abstract A rapid, simple, and specific method was developed for the diagnosis of congenital adrenal hyperplasia (CAH) from dried blood spots on newborn screening cards based on high-performance liquid chromatography/electrospray ionization tandem mass spectrometry (HPLC/ESI-MS/MS). The usefulness of 17,-hydroxyprogesterone (17OH-P) determination on dried filter-paper blood samples from patients with CAH caused by 21-hydroxylase deficiency was evaluated. The LC/MS/MS detection of 17OH-P was rapid, <4 min. The intra- and interday accuracy and precision of the method were <7%. Our procedure maintained good linearities (R2 > 0.992) and recovery rate (>83%). We used this new method to directly determine the 17OH-P levels in dried blood specimens from abnormal children of various ages, with a detection limit of 20 ng/ml (,240 pg), to avoid the time-consuming derivatization steps required by the gas-chromatography/mass spectrometry (GC/MS) method. Four dried filter-paper blood samples of CAH patients (three girls and one boy, 1,14 years old) were all quantified in an LC/MS/MS study and revealed high 17OH-P levels (>90 ng/ml). After treatment, all of the elevated 17OH-P levels either decreased or disappeared. Compared with CAH patients, 17OH-P was nearly undetectable (<20 ng/ml) in the normal infants by LC/MS/MS. This LC/MS/MS assay is not only useful for both diagnosis and monitoring of treatment of CAH in all other age groups, it also can be used as a screening test for CAH infants. In this study, we provided the first data on 17OH-P in dried blood specimens affected with CAH using HPLC/ESI-MS/MS. J. Clin. Lab. Anal. 16:20,25, 2002. © 2002 Wiley-Liss, Inc. [source] Rapid screening and characterization of drug metabolites using a new quadrupole,linear ion trap mass spectrometerJOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 2 2003Gérard Hopfgartner Abstract The application of a new hybrid RF/DC quadrupole,linear ion trap mass spectrometer to support drug metabolism and pharmacokinetic studies is described. The instrument is based on a quadrupole ion path and is capable of conventional tandem mass spectrometry (MS/MS) as well as several high-sensitivity ion trap MS scans using the final quadrupole as a linear ion trap. Several pharmaceutical compounds, including trocade, remikiren and tolcapone, were used to evaluate the capabilities of the system with positive and negative turbo ionspray, using either information-dependent data acquisition (IDA) or targeted analysis for the screening, identification and quantification of metabolites. Owing to the MS/MS in-space configuration, quadrupole-like CID spectra with ion trap sensitivity can be obtained without the classical low mass cutoff of 3D ion traps. The system also has MS3 capability which allows fragmentation cascades to be followed. The combination of constant neutral loss or precursor ion scan with the enhanced product ion scan was found to be very selective for identifying metabolites at the picogram level in very complex matrices. Owing to the very high cycle time and, depending on the mass range, up to eight different MS experiments could be performed simultaneously without compromising chromatographic performance. Targeted product ion analysis was found to be complementary to IDA, in particular for very low concentrations. Comparable sensitivity was found in enhanced product ion scan and selected reaction monitoring modes. The instrument is particularly suitable for both qualitative and quantitative analysis. Copyright © 2003 John Wiley & Sons, Ltd. [source] Rapid screening of beta-adrenergic agents and related compounds in human urine for anti-doping purpose using capillary electrophoresis with dynamic coatingJOURNAL OF SEPARATION SCIENCE, JSS, Issue 20 2009Monica Mazzarino Abstract This paper presents a capillary electrophoresis method, developed for the detection, in human urine, of beta-adrenergic agents and phenolalkylamines. The electrophoretic separation is achieved in less than 10 min and is based on the use of CEofix kit, for the dynamic capillary coating. The effects of accelerator buffer pH and separation voltage were investigated. The optimum buffer pH was found to be 2.5 for beta2-agonists and 6.2 for beta-blockers and phenoalkylamines with a separation voltage of 15 kV. Urine samples spiked with the compounds here studied were treated according to the standard procedure (SPE and evaporation to dryness) and analyzed by CE interfaced with an UV diode-array, set at 195 and 210 nm. The quantitative validation results, obtained analyzing samples at three different concentrations, show a good precision of peak areas that do not exceed 5% for intra-day assays and 10% for inter-day assays. Good linearity (r2 > 0.995) was obtained within the 50,500 ng/mL concentration range. The qualitative validation data show a relative migration times (MTs) variation lower than 1%. The analytes were clearly distinguishable in urine, with LOD and LOQ in the range of 10,80 and 40,100 ng/mL, respectively. [source] Rapid screening and confirmation of drugs and toxic compounds in biological specimens using liquid chromatography/ion trap tandem mass spectrometry and automated library searchRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 1 2010Hsiu-Chuan Liu Recent advances in liquid chromatography/tandem mass spectrometry (LC/MS/MS) technology have provided an opportunity for the development of more specific approaches to achieve the ,screen' and ,confirmation' goals in a single analytical step. For this purpose, this study adapts the electrospray ionization ion trap LC/MS/MS instrumentation (LC/ESI-MS/MS) for the screening and confirmation of over 800 drugs and toxic compounds in biological specimens. Liquid-liquid and solid-phase extraction protocols were coupled to LC/ESI-MS/MS using a 1.8-µm particle size analytical column operated at 50°C. Gradient elution of the analytes was conducted using a solvent system composed of methanol and water containing 0.1% formic acid. Positive-ion ESI-MS/MS spectra and retention times for each of the 800 drugs and toxic compounds were first established using 1,10,µg/mL standard solutions. This spectra and retention time information was then transferred to the library and searched by the identification algorithm for the confirmation of compounds found in test specimens , based on retention time matches and scores of fit, reverse fit, and purity resulting from the searching process. The established method was found highly effective when applied to the analyses of postmortem specimens (blood, urine, and hair) and external proficiency test samples provided by the College of American Pathology (CAP). The development of this approach has significantly improved the efficiency of our routine laboratory operation that was based on a two-step (immunoassay and GC/MS) approach in the past. Copyright © 2009 John Wiley & Sons, Ltd. [source] Rapid screening of clenbuterol in urine samples by desorption electrospray ionization tandem mass spectrometryRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 12 2008Ziqing Lin Rapid screening of clenbuterol in urine was performed by combining desorption electrospray ionization (DESI) and tandem mass spectrometry (MS/MS). Optimization experiments were carried out including the selection of substrates, spray solutions, nebulizing gas pressures, high-voltage power supplies and flow rates of spray solution. The limit of detection (LOD), defined as the lowest quantity that can be detected, was 5.0 pg for the pure compound. Using DESI coupled with solid-phase extraction (SPE), the linear response range was from 10 to 400,ng/mL (R2,=,0.993) and the concentration LOD for urine sample was 2.0,ng/mL. The analysis for one spiked urine sample was achieved within 4,min. In addition to the fast analysis speed, MS/MS provided structural information for the confirmation of clenbuterol. Urine samples from different people were investigated and the recoveries were within 100,±,20%. The developed method can potentially be used for screening of clenbuterol in doping control. Copyright © 2008 John Wiley & Sons, Ltd. [source] Electrospray ionization with ambient pressure ion mobility separation and mass analysis by orthogonal time-of-flight mass spectrometryRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 23 2001Wes E. Steiner Rapid screening and identification of drug and other mixtures are possible using a novel ambient pressure high-resolution ion mobility (APIMS) orthogonal reflector time-of-flight mass spectrometer (TOFMS). Departing ions from the APIMS drift tube traversed a pressure interface between the APIMS and TOFMS where they were subjected to numerous gas collisions that could produce selective fragmentation. By increasing the accelerating field in the pressure interface region, the ions generated using water-cooled electrospray ionization (ESI) underwent collision-induced dissociation (CID). Mixtures of ESI ions were separated by APIMS based on their respective size-to-charge (s/z) ratios while CID and analysis of mass-to-charge (m/z) ratios occurred in the pressure interface and TOFMS. Product ions that were formed in this pressure interface region could be readily assigned to precursor ions by matching the mobility drift times. This process was demonstrated by the examination of a mixture of amphetamines and the resulting fragmentation patterns of the mobility-separated precursor ion species [M,+,H]+. Copyright © 2001 John Wiley & Sons, Ltd. [source] Rapid screening of polysaccharide-based plasma volume expanders dextran and hydroxyethyl starch in human urine by liquid chromatography,tandem mass spectrometryBIOMEDICAL CHROMATOGRAPHY, Issue 7 2008Sven Guddat Abstract The increasing number of samples and target substances in doping control requires continuously improved screening methods, combining high-throughput analysis, simplified sample preparation, robustness and reliability. Hence, a rapid screening procedure based on liquid chromatography,electrospray ionization,tandem mass spectrometry with in-source collision-induced dissociation was developed. The detection of the polysaccharide-based plasma volume expanders dextran and hydroxyethyl starch (HES) in human urine was established without further sample preparation. The in-source fragmentation strategy of the approach represented a valuable tool in the analysis of the polysaccharide-based compounds, allowing the use of tandem mass spectrometry. After direct injection of urine specimens, analytes were chromatographically separated on a monolithic reverse-phase column and detected via multiple reaction monitoring of diagnostic ions at detection limits of 10 µg/mL for HES and 30 µg/mL for dextran. Validation was performed regarding the parameters specificity, linearity, precision (8,18%) and accuracy (77,105%) and the method was applied to the investigation of approximately 400 doping control samples and seven dextran and two hydroxyethyl starch post-administration samples. The approach demonstrated its capability as a rapid screening tool for the detection of dextran and hydroxyethyl starch and represents an alternative to existing screening procedures since time consuming hydrolysis or derivatization steps were omitted. Copyright © 2008 John Wiley & Sons, Ltd. [source] High-throughput screening of chemical exchange saturation transfer MR contrast agentsCONTRAST MEDIA & MOLECULAR IMAGING, Issue 3 2010Guanshu Liu Abstract A new high-throughput MRI method for screening chemical exchange saturation transfer (CEST) agents is demonstrated, allowing simultaneous testing of multiple samples with minimal attention to sample configuration and shimming of the main magnetic field (B0). This approach, which is applicable to diamagnetic, paramagnetic and liposome CEST agents, employs a set of inexpensive glass or plastic capillary tubes containing CEST agents put together in a cheap plastic tube holder, without the need for liquid between the tubes to reduce magnetic susceptibility effects. In this setup, a reference image of direct water saturation spectra is acquired in order to map the absolute water frequency for each volume element (voxel) in the sample image, followed by an image of saturation transfer spectra to determine the CEST properties. Even though the field over the total sample is very inhomogeneous due to air,tube interfaces, the shape of the direct saturation spectra is not affected, allowing removal of susceptibility shift effects from the CEST data by using the absolute water frequencies from the reference map. As a result, quantitative information such as the mean CEST intensity for each sample can be extracted for multiple CEST agents at once. As an initial application, we demonstrate rapid screening of a library of 16 polypeptides for their CEST properties, but in principle the number of tubes is limited only by the available signal-noise-ratio, field of view and gradient strength for imaging. Copyright © 2010 John Wiley & Sons, Ltd. [source] Rapid (partial) prescreening of cervical smears: the quality control method of choice?CYTOPATHOLOGY, Issue 4 2002D. BROOKE Rapid rescreening of all negative and inadequate smears is the quality control method of choice in the UK. The sensitivity of primary screening of laboratory and individual screeners are major indicators of screening quality and are dependent on the number of false negative smears found by rapid screening for their calculation. High sensitivity may indicate good quality primary screening or poor quality rapid review. Quantifiably high quality rapid rescreening is essential if these sensitivity figures are to be meaningful. A 12-month study was undertaken in routine practice using the prescreening mode to ascertain the sensitivity of rapid (partial) screening in our department . The final results of smears were compared with those of rapid prescreening. The calculated sensitivity ranged from 92,54% for high-grade abnormalities and 75,33% for all grades, revealing a wide range of performance between individual prescreeners. Rapid prescreening can identify individuals best suited to rapid screening in routine practice. By using these prescreeners only, the sensitivity of cervical screening could be raised. Rapid (partial) prescreening should be considered as the quality control method of choice. [source] A rapid screening LC-MS/MS method based on conventional HPLC pumps for the analysis of low molecular weight xenobiotics: application to doping control analysisDRUG TESTING AND ANALYSIS, Issue 7 2010Monica Mazzarino Abstract This study presents a fast multi-analyte screening method specifically developed for the detection of xenobiotics in urine. The proposed method allows the screening of several classes of substance in a single chromatographic method with a run-time of 11 min, inclusive of post-run and reconditioning times. Chromatographic separation is achieved in 7.2 min using a reversed-phase 2.7 µm fused-core particle column, generating a back-pressure not exceeding 400 bar and therefore enabling the use of traditional high performance liquid chromatography (HPLC) instruments. The effectiveness of this approach was evaluated, by liquid-chromatography tandem mass spectrometry (LC-MS/MS) in positive electrospray ionization, using 20 blank urine samples spiked with 45 compounds prohibited in sport: 11 diuretics, 16 glucocorticoids, 9 stimulants, 5 anti-oestrogens, as well as formoterol, carboxy-finasteride (previously prohibited by the World Anti-Doping Agency (WADA) in 2008), gestrinone and tetrahydrogestrinone. Qualitative validation shows the proposed method to be specific with no significant interference. All of the analytes considered in this study were clearly distinguishable in urine, with limits of detection ranging from 5 ng/mL to 350 ng/mL, significantly below the Minimum Required Performance Levels (MRPL) set by WADA for the accredited sports anti-doping laboratories. All compounds of interest were separated, including synthetic and endogenous glucocorticoids with similar retention times and fragmentation patterns. Copyright © 2010 John Wiley & Sons, Ltd. [source] Impedance Spectroscopy: A Powerful Tool for Rapid Biomolecular Screening and Cell Culture MonitoringELECTROANALYSIS, Issue 23 2005Isaac Abstract Dielectric spectroscopy or Electrochemical impedance spectroscopy (EIS) is traditionally used in corrosion monitoring, coatings evaluation, batteries, and electrodeposition and semiconductor characterization. However, in recent years, it is gaining widespread application in biotechnology, tissue engineering, and characterization of biological cells, disease diagnosis and cell culture monitoring. This article discusses the principles and implementation of dielectric spectroscopy in these bioanalytical applications. It provides examples of EIS as label-free, mediator-free strategies for rapid screening of biocompatible surfaces, monitoring pathogenic bacteria, as well as the analysis of heterogeneous systems, especially biological cells and tissues. Descriptions are given of the application of nanoparticles to improve the analytical sensitivities in EIS. Specific examples are given of the detection of base pair mismatches in the DNA sequence of Hepatitis B disease, TaySach's disease and Microcystis spp. Others include the EIS detection of viable pathogenic bacteria and the influence of nanomaterials in enhancing biosensor performance. Expanding applications in tissue engineering such as adsorption of proteins onto thiolated hexa(ethylene glycol)-terminated (EG6) self-assembled monolayer (SAM) are discussed. [source] Induction of cytochrome P4501A in African brown house snake (Lamprophis fuliginosus) primary hepatocytesENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 2 2006Markus Hecker Abstract Ahough there have been numerous sudies involving fish, birds, and mammals, little is known about the response of the cytochrome P4501A system of snakes to halogenated aromatic hydrocarbons (HAHs). The present study describes the induction of ethoxyresorufin- O -deethylase (EROD) in primary hepatocytes of the African brown house snake (Lamprophis fuliginosus). Hepatocytes were exposed in multiwell plates to 2,3,7,8-tetrachlorodibenzo- p -dioxin (TCDD) and four different non- ortho -substi-tuted coplanar polychlorinated biphenyls (PCBs 77, 81, 126, and 169). Exposure to TCDD and PCB 126 resulted in a dose-dependent increase in EROD activity, with maximum inducible EROD activities of 177 ± 56 (mean ± SEM) and 101.1 ± 55 pmol/min/mg protein for TCDD and PCB 126, respectively. None of the other PCBs caused a measurable induction of EROD, which suggests reduced inducibility of snake hepatocytes compared to some vertebrate taxa. Median effective concentrations (EC50s) were 0.16 ± 0.03 nM for TCDD and 8.25 ± 4.14 nM for PCB 126. The relative potency (REP20,80) range for PCB 126 was 0.044 to 0.046. Compared to results from in vitro systems using other vertebrate species, both the maximum inducibility and the REPs estimated for L. fuliginosus were within the same range as those reported for mammals and the more sensitive bird species but were greater than the values reported for most fish species. In conclusion, induction of EROD activity in primary hepatocytes appears to be a useful approach for evaluating the dioxin-like potencies of aryl hydrocarbon,receptor agonists in snakes. The test system offers a method for rapid screening of reptilian responsiveness to these compounds using smaller numbers of organisms than with in vivo studies, an important consideration for many declining reptile species. [source] A single question for the rapid screening of restless legs syndrome in the neurological clinical practiceEUROPEAN JOURNAL OF NEUROLOGY, Issue 9 2007R. Ferri The purposes of this study were to validate the use of a single standard question for the rapid screening of restless legs syndrome (RLS) and to analyze the eventual effects of the presence of RLS on self-assessed daytime sleepiness, global clinical severity and cognitive functioning. We evaluated a group of 521 consecutive patients who accessed our neurology clinic for different reasons. Beside the answer to the single question and age, sex, and clinical diagnosis, the following items were collected from all patients and normal controls: the four criteria for RLS, the Epworth Sleepiness Scale (ESS), the Clinical Global Impression of Severity (CGI-S), and the Mini-Mental State evaluation. RLS was found in 112 patients (70 idiopathic). The single question had 100% sensitivity and 96.8% specificity for the diagnosis of RLS. ESS and CGI-S were significantly higher in both RLS patient groups than in normal controls. RLS severity was significantly higher in idiopathic than in associated/symptomatic RLS patients. RLS can be screened with high sensitivity and good reliability in large patient groups by means of the single question; however, the final diagnosis should always be confirmed by the diagnostic features of RLS and accompanied by a careful search for comorbid conditions. [source] Validation of the CDC biofilm reactor as a dynamic model for assessment of encrustation formation on urological device materialsJOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 1 2010Brendan F. Gilmore Abstract Contemporary medical science is reliant upon the rational selection and utilization of devices, and therefore, an increasing need has developed for in vitro systems aimed at replicating the conditions to which urological devices will be subjected to during their use in vivo. We report the development and validation of a novel continuous flow encrustation model based on the commercially available CDC biofilm reactor. Proteus mirabilis -induced encrustation formation on test biomaterial sections under varying experimental parameters was analyzed by X-ray diffraction, infrared- and Raman spectroscopy and by scanning electron microscopy. The model system produced encrusted deposits similar to those observed in archived clinical samples. Results obtained for the system are highly reproducible with encrustation being rapidly deposited on test biomaterial sections. This model will have utility in the rapid screening of encrustation behavior of biomaterials for use in urological applications. © 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2010 [source] Investigation of multiphase hydrogenation in a catalyst-trap microreactorJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 3 2009S. McGovern BACKGROUND: Multiphase hydrogenation plays a critical role in the pharmaceutical industry. A significant portion of the reaction steps in a typical fine chemical synthesis are catalytic hydrogenations, generally limited by resistances to mass and heat transport. To this end, the small-scale and large surface-to-volume ratios of microreactor technology would greatly benefit chemical processing in the pharmaceutical and other industries. A silicon microreactor has been developed to investigate mass transfer in a catalytic hydrogenation reaction. The reactor design is such that solid catalyst is suspended in the reaction channel by an arrangement of catalyst traps. The design supports the use of commercial catalyst and allows control of pressure drop across the bed by engineering the packing density. RESULTS: This paper discusses the design and operation of the reactor in the context of the liquid-phase hydrogenation of o-nitroanisole to o-anisidine. A two-phase ,flow map' is generated across a range of conditions depicting three flow regimes, termed gas-dominated, liquid-dominated, and transitional, all with distinctly different mass transfer behavior. Conversion is measured across the flow map and then reconciled against the mass transfer characteristics of the prevailing flow regime. The highest conversion is achieved in the transitional flow regime, where competition between phases induces the most favorable gas,liquid mass transfer. CONCLUSION: The results are used to associate a mass transfer coefficient with each flow regime to quantify differences in performance. This reactor architecture may be useful for catalyst evaluation through rapid screening, or in large numbers as an alternative to macro-scale production reactors. Copyright © 2008 Society of Chemical Industry [source] Computational alanine scanning of the 1:1 human growth hormone,receptor complexJOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 1 2002Shuanghong Huo Abstract The MM-PBSA (Molecular Mechanics,Poisson,Boltzmann surface area) method was applied to the human Growth Hormone (hGH) complexed with its receptor to assess both the validity and the limitations of the computational alanine scanning approach. A 400-ps dynamical trajectory of the fully solvated complex was simulated at 300 K in a 101 Å×81 Å×107 Å water box using periodic boundary conditions. Long-range electrostatic interactions were treated with the particle mesh Ewald (PME) summation method. Equally spaced snapshots along the trajectory were chosen to compute the binding free energy using a continuum solvation model to calculate the electrostatic desolvation free energy and a solvent-accessible surface area approach to treat the nonpolar solvation free energy. Computational alanine scanning was performed on the same set of snapshots by mutating the residues in the structural epitope of the hormone and the receptor to alanine and recomputing the ,Gbinding. To further investigate a particular structure, a 200-ps dynamical trajectory of an R43A hormone,receptor complex was simulated. By postprocessing a single trajectory of the wild-type complex, the average unsigned error of our calculated ,,Gbinding is ,1 kcal/mol for the alanine mutations of hydrophobic residues and polar/charged residues without buried salt bridges. When residues involved in buried salt bridges are mutated to alanine, it is demonstrated that a separate trajectory of the alanine mutant complex can lead to reasonable agreement with experimental results. Our approach can be extended to rapid screening of a variety of possible modifications to binding sites. © 2002 Wiley Periodicals, Inc. J Comput Chem 23: 15,27, 2002 [source] Antagonistic Activity of Spent Culture Supernatants of Lactic Acid Bacteria against,Helicobacter Pylori,Growth and Infection in Human Gastric Epithelial AGS CellsJOURNAL OF FOOD SCIENCE, Issue 6 2009Wen-Hsin Lin ABSTRACT:, We investigated the bactericidal activity and exclusion effect of 10 strains of lactic acid bacteria (LAB) isolated from different commercial food products and infant feces against,Helicobacter pylori,(H. pylori) in human gastric epithelial AGS cells. Antagonistic activity of spent culture supernatants (SCS) from LAB (LAB-SCS) was tested, and the content of organic acids in SCS was analyzed with high-performance liquid chromatography (HPLC). In addition, the bactericidal activities of LAB-SCS were estimated by a time-kill assay and by measuring the exclusion effect of LAB-SCS against,H. pylori,in AGS cells. The results showed that SCS from certain strains with higher concentrations of organic acids dramatically decreased the viability of,H. pylori. We also proved that the organic acids could inhibit,H. pylori,adhesion and invasion of AGS cells. Furthermore, the concentration and speciation of organic acids in SCS after fermentation of LAB are important factors in the inhibition of,H. pylori,infection. In addition, the,in vitro,methods used in this study might provide for the rapid screening of potential probiotics with anti- H. pylori,activity in the dairy industry. [source] Newborn screening in Fragile X syndromeJOURNAL OF INTELLECTUAL DISABILITY RESEARCH, Issue 10 2008F. Tassone Background: Screening for the FMR1 mutations has been a topic of considerable discussion since the FMR1 gene was identified. However, Fragile X has not been recommended for newborn screening mainly because of the lack of an accurate screening test and of data on potential benefits. We have recently developed an improved Polymerase Chain Reaction (PCR) method for the identification of premutation and full mutation alleles for the FMR1 gene. Method: The method is inexpensive, accurate and quick and can be performed on a number of sample templates including, importantly, blood spots. We have applied this method for international screening. Specifically, we have screened 5267 anonymous blood spot samples from newborn males from the centre-northwest region of Spain. We have also used this technology to a pilot ,high risk' screening program of individuals with autism and/or intellectual disabilities and family members of a proband with fragile X initiated in Guatemala. This project is a prototype for future screening endeavours. Results: One important outcome from this study is that the frequency of premutation alleles (1 per 250) appears to be higher than previously reported. This is of importance, especially in view of the different phenotypic involvement observed in carriers of premutation alleles, including neurological problems such as FXTAS. Here, we present data on the frequency of premutation/full alleles found in this population and their size distribution. Conclusion: This project is a prototype for future screening endeavours. Results from our pilot program in both Spain and Guatemala will lend strong support for implementing this technology for rapid screening to a much larger scale population screening. [source] Evaluation of the reduction of imidazophenazine dye derivatives under fast-atom-bombardment mass-spectrometric conditions,JOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 1 2006Marina V. Kosevich Abstract Satellite [M + 2]+, and [M + 3]+ peaks accompanying the common peak of the protonated molecule [M + H]+ that are known to indicate the occurrence of a reduction process were observed in the fast atom bombardment (FAB) mass spectra of imidazophenazine dye derivatives in glycerol matrix. The distribution of the abundances in the [M + nH]+ peak group varied noticeably for different derivatives. This indicated different levels of the reduction depending on the different structure variations of the studied molecules. In the search for correlations between the mass spectral pattern and the structural features of the dyes, ab initio HF/6-31++G** quantum chemical calculations were performed. They revealed that the abundances of the [M + 2]+, and [M + 3]+ ions show growth proportional to the decrease of the energy of the lowest unoccupied molecular orbital, i.e. proportional to the increase of the electron affinity of the dye molecule. A method for rapid screening of reductive properties of sets of dye derivatives on the basis of the FAB mass spectral data is discussed. Copyright © 2005 John Wiley & Sons, Ltd. [source] Screening of antioxidant phenolic compounds in Chinese Rhubarb combining fast counter-current chromatography fractionation and liquid chromatography/mass spectrometry analysisJOURNAL OF SEPARATION SCIENCE, JSS, Issue 11 2010Ruilin Hu Abstract In this paper, an effective method combing fast elution-extrusion counter-current chromatography (CCC) and LC/MS for rapid screening of antioxidative phenolic compounds in Chinese Rhubarb is presented. An integrated three-coil CCC column (40,mL each coil) was used to accomplish the optimization of biphasic liquid system. In a single run (approximately 40,min), the solvent system composed of n -hexane/ethyl acetate/methanol/water (1:1:1:1, v/v) was selected as optimum CCC liquid system for fast fractionation of the crude ethanol extract. With a 140,mL-capacity CCC instrument, 100,mg Chinese Rhubarb extract was separated under the optimized conditions, producing six fractions in only 100,min. The quantities of each fraction were ,15,mg. In addition, each fraction was subjected to antioxidant activity assay and characterized by LC/MS analysis. Fifty compounds, including phenolic acids, phenolic glucosides and hydroxyanthraquinones, were detected by LC/MS/MS analysis. As a result, gallic acid together with Fr I showed excellent antioxidant activity, which was well consistent with previous studies and exhibited great potential for natural drug discovery program of the present method. [source] Composition and radical-scavenging activity of Thymus glabrescens Willd. (Lamiaceae) essential oilJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 11 2008Zoran Maksimovi Abstract BACKGROUND: Knowledge about the chemical and therapeutic properties of Thymus glabrescens Willd. (Lamiaceae) is scarce and inconsistent. Therefore the main objectives of this study were to determine the yield and chemical composition of essential oils from wild-growing T. glabrescens populations, to assess their radical scavenging activity and to correlate the results with published data in order to deduce which components are responsible for the activity. RESULTS: The plant material yielded between 4.0 and 8.0 mL kg,1 of essential oil. All samples contained considerable but variable concentrations of thymol (22.3,55.1%), depending on the source. Radical-scavenging activities of the oils were estimated by 1,1-diphenyl-2-picrylhydrazyl free radical (DPPH) assay against butylated hydroxytoluene (BHT) and thymol as positive controls. The observed activities (IC50 values ranged from 94 to 230 µg mL,1) were strongly influenced by thymol concentration, as verified by rapid screening for DPPH radical-scavenging activity on thin layer chromatography (TLC) plates and regression analysis. CONCLUSION: These results represent the first report on the free radical-scavenging activity of T. glabrescens essential oil and one of the first comprehensive reports on its composition. Thymus glabrescens could be used in the food industry for seasoning purposes or for preserving processed foods from oxidative degradation. Copyright © 2008 Society of Chemical Industry [source] Prediction of fat in intact cereal food products using near-infrared reflectance spectroscopy,JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 9 2005Sandra E Kays Abstract To evaluate the feasibility of an intact product approach to the near-infrared (NIR) determination of fat content, a rapid acquisition spectrometer, with an InGaAs diode-array detector and custom built sampling device, was used to obtain reflectance spectra (1100,1700 nm) of diverse cereal food products. Fat content reference data were obtained gravimetrically by extraction with petroleum ether (AOAC Method 945.16). Using spectral and reference data, partial least-squares regression analysis was applied to calculate a NIR model (n = 89) to predict fat in intact cereal products; the model was adequate for rapid screening of samples, predicting the test samples (n = 44) with root mean square error of prediction (RMSEP) of 11.8 (range 1.4,204.8) g kg,1 and multiple coefficient of determination of 0.98. Repeated repacking and rescanning of the samples did not appreciably improve model performance. The model was expanded to include samples with a broad range of particle sizes and moisture contents without reduction in prediction accuracy for the untreated samples. The regression coefficients for the models calculated indicated that spectral features at 1165, 1215 and 1395 nm, associated with CH stretching in fats, were the most critical for model development. Published in 2005 for SCI by John Wiley & Sons, Ltd. [source] Detection, isolation and characterization of Shiga toxin-producing Escherichia coli in retail-minced beef using PCR-based techniques, immunoassays and colony hybridizationLETTERS IN APPLIED MICROBIOLOGY, Issue 6 2007F. Auvray Abstract Aims:, To provide information on detection of Shiga toxin-producing Escherichia coli (STEC) in retail-minced beef using an approach combining (i) PCR-based techniques and automated immunoassay for stx screening and detection of the five major serogroups associated with human infection, and (ii) immunomagnetic separation (IMS) and colony hybridization assays for bacterial strain isolation. Methods and Results:, Twenty-seven out of 164 minced beef samples were stx -positive by PCR-ELISA, nine of which were also positive by real-time PCR for at least one marker of the five main serogroups tested (O26, O103, O111, O145 and O157). Two E. coli O103 stx -negative strains were isolated from two out of 10 IMS and nine STEC strains that did not belong to the five main serogroups were isolated by colony hybridization. Conclusions:, PCR techniques are applicable for rapid screening of samples containing both an stx gene and an O-group marker of the five main pathogenic STEC serogroups. Isolation of STEC strains belonging to the main non-O157 serogroups remains difficult. Significance and Impact of the Study:, This study presents an evaluation of a multi-faceted approach for the detection of the most frequently reported human pathogenic STEC serogroups. The advantages and limits of this strategy are presented. [source] 15N NMR spectroscopy as a method for comparing the rates of imidization of several diamines,POLYMER COMPOSITES, Issue 6 2006James C. Johnston The relative rates of the conversion of amide-acid to imide were measured for a series or aromatic diamines that have been identified as potential replacements for 4,4,-methylene dianiline (MDA) in high-temperature polyimides and polymer composites. These rates were compared with the 15N NMR resonances of the unreacted amines. The initial rates of imidization track with the difference in chemical shift between the amine nitrogens in MDA and those in the subject diamines. This comparison demonstrated that 15N NMR spectroscopy is appropriate for the rapid screening of candidate diamines to determine their reactivity relative to MDA, and can serve to provide guidance to the process of creating the time,temperature profiles used in processing these materials into polymer matrix composites. POLYM. COMPOS. 27:723,729, 2006. © 2006 Society of Plastics Engineers [source] | ||||||||||||||||||||||||||||||||||