986 resultados para COUNTER-CURRENT CHROMATOGRAPHY


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A rapid, sensitive and specific LC-MS/MS method was developed and validated for quantifying chlordesmethyldiazepam (CDDZ or delorazepam), the active metabolite of cloxazolam, in human plasma. In the analytical assay, bromazepam (internal standard) and CDDZ were extracted using a liquid-liquid extraction (diethyl-ether/hexane, 80/20, v/v) procedure. The LC-MS/MS method on a RP-C18 column had an overall run time of 5.0 min and was linear (1/x weighted) over the range 0.5-50 ng/mL (R > 0.999). The between-run precision was 8.0% (1.5 ng/mL), 7.6% (9 ng/mL), 7.4% (40 ng/mL), and 10.9% at the low limit of quantification-LLOQ (0.500 ng/mL). The between-run accuracies were 0.1, -1.5, -2.7 and 8.7% for the above mentioned concentrations, respectively. All current bioanalytical method validation requirements (FDA and ANVISA) were achieved and it was applied to the bioequivalence study (Cloxazolam-test, Eurofarma Lab. Ltda and Olcadil (R)-reference, Novartis Biociencias S/A). The relative bioavailability between both formulations was assessed by calculating individual test/reference ratios for Cmax, AUClast and AUCO-inf. The pharmacokinetic profiles indicated bioequivalence since all ratios were as proposed by FDA and ANVISA. Copyright (C) 2009 John Wiley & Sons, Ltd.

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In the wake of the Bali bombing the Australian government has proposed a number of national security measures that pose a real danger to human security in Australia and the region. These measures include renewed and increased military and intelligence exchanges with Indonesia, and laws that allow the Australian Security Intelligence Organization (ASIO) to detain people without charge or even suspicion in order to gather intelligence. In less emotional times these initiatives would be rejected as contrary to human rights concerns and Australia’s democratic traditions, which include the rule of law and due process protections. In the current climate, however, human rights and civil liberties are apt to be portrayed as unaffordable luxuries.

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Many modulation systems in comprehensive 2D GC (GC×GC) are based on cryogenic methods. High trapping temperatures in these systems can result in ineffective trapping of the more volatile compounds, whilst temperatures that are too low can prevent efficient remobilisation of some compounds. To better understand the trapping and release of compounds over a wide range of volatilities, we have investigated a number of different constant temperature modulator settings, and have also examined a constant temperature differential between the cryo-trap and the chromatographic oven. These investigations have led us to modify the temperature regulation capabilities of the longitudinally modulated cryogenic system (LMCS). In contrast to the current system, where the user sets a constant temperature for the cooling chamber, the user now sets the temperature difference between the cryo-trap and the chromatographic oven. In this configuration, the cooling chamber temperature increases during the chromatographic run, tracking the oven temperature ramp. This produces more efficient, volatility-dependent modulation, and increases the range of volatile compounds that can be analysed under optimal trap-and-release conditions within a single analytical run. This system also reduces cryogenic fluid consumption.

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C1 and phenyl-type stationary phases were assessed in terms of their environmental impact on separations using as test solutes polycyclic aromatic hydrocarbons. Methanol (MeOH) and acetonitrile (ACN) mobile-phase gradients were employed. These stationary phases were examined to determine if different physical and chemical properties possessed by these surfaces decreased the organic solvent consumption, and yet maintained peak capacity. The cumulative energy demand (CED) was used to gauge the environmental impact of the separations. The separation of the polycyclic aromatic hydrocarbon test mixture using current methodologies (i.e. a C18/ACN combination) had a CED of 1.13 MJ-eq, and a peak capacity of 27 peaks (resolving 7 of 12 peak pairs with Rs>1). In comparison, a butyl phenyl stationary phase with a methanol mobile phase had a peak capacity of 26, but with a CED of 0.670 MJ-eq. Monolithic columns containing C18 and C1 phases were also tested. A monolithic C18 column with MeOH had the lowest CED at 0.675 MJ-eq, a peak capacity of 28 peaks and good resolving power (resolving ten peak pairs with Rs>1), suggesting that this is a viable option with respect to reducing environmental impact for these types of analyses.

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Improvised Explosive Devices (IEDs) are reported as the number one cause of injury and death for allied troops in the current theater of operation. Deakin University’s Centre for Intelligent Systems Research (CISR) is working on next-generation technology to combat the threat. In 2006 CISR was awarded funding through the Capability and Technology Demonstrator (CTD) Program managed by the Australian Defence Force. The objective was to investigate the use of haptics or force feedback technology for Counter-IED (CIED) tasks. Over the past six years, engineers from CISR have worked alongside Defence stakeholders to develop a series of robotic platforms designed to immerse a soldier in the remote environment. Utilising a natural user interface, haptic force feedback and stereovision, the technology has undergone initial trials in Sydney, Canberra, Woomera and at the CISR testing facility in Geelong, Australia. The technology has proved popular among operators allowing them increased fidelity and manipulation speed while significantly reducing required training. CISR has a history of rapidly delivering technology to meet the needs of police and law enforcement in Australia. The OzBot™ series of robots developed in conjunction with the Victorian Police is currently in service and used extensively for hostage negotiation and first responder roles. The CISR robotics group works on technologies that reduce operator fatigue, minimise training liability and maintenance. Over 55 engineers develop simulation environments for increased training availability and continuous improvement to the current range of mobile platforms, including communications range, payload, manipulator reach and capability. This paper describes a number of the technologies, methods and systems developed by CISR for IED neutralisation, with the aim to increasing military awareness of Australian capability.

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Occurrence and the effects of butyltin compounds (BTs) have been studied for some years, mainly in countries of the Northern Hemisphere. Due to widespread use of tributyltin compounds (TBTs) and considering their deleterious effects, it is necessary to conduct studies on its occurrence, especially in the marine environment because of its excessive use in coatings of ship hulls to prevent fouling. Moreover, it was important to extend the evaluation to areas where there is no current information about their occurrence. The present work reports the occurrence of BTs in marine sediments of São Paulo state, Brazil. Commercial and leisure harbor sampling sites were selected because these areas are potentially exposed to BTs from antifouling paints used on ship hulls. Analytical conditions for organotin analysis in marine sediments were optimized for GC with pulsed flame photometric detection. Detection limits ranged from 8.4 to 66.3 ng g(-1) using a 610-nm filter, and the linearity range was 20-500 ng g(-1). Concentration levels of BTs were highest in Santos harbor (360 ng g(-1) TBT in average) and Guaruja marina (670 ng g(-1) TBT in average), which seems to be related to intensive boat traffic. Lower levels of BTs were observed in Cananeia, where only fishing boats are present (50 ng g(-1) TBT in average). (C) 2002 Elsevier B.V. B.V. All rights reserved.

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BACKGROUND Sudden infant death syndrome (SIDS) is a leading cause of death during the first 6 months after birth. About 5% to 10% of SIDS may stem from cardiac channelopathies such as long-QT syndrome. We recently implicated mutations in alpha1-syntrophin (SNTA1) as a novel cause of long-QT syndrome, whereby mutant SNTA1 released inhibition of associated neuronal nitric oxide synthase by the plasma membrane Ca-ATPase PMCA4b, causing increased peak and late sodium current (I(Na)) via S-nitrosylation of the cardiac sodium channel. This study determined the prevalence and functional properties of SIDS-associated SNTA1 mutations. METHODS AND RESULTS Using polymerase chain reaction, denaturing high-performance liquid chromatography, and DNA sequencing of SNTA1's open reading frame, 6 rare (absent in 800 reference alleles) missense mutations (G54R, P56S, T262P, S287R, T372M, and G460S) were identified in 8 (approximately 3%) of 292 SIDS cases. These mutations were engineered using polymerase chain reaction-based overlap extension and were coexpressed heterologously with SCN5A, neuronal nitric oxide synthase, and PMCA4b in HEK293 cells. I(Na) was recorded using the whole-cell method. A significant 1.4- to 1.5-fold increase in peak I(Na) and 2.3- to 2.7-fold increase in late I(Na) compared with controls was evident for S287R-, T372M-, and G460S-SNTA1 and was reversed by a neuronal nitric oxide synthase inhibitor. These 3 mutations also caused a significant depolarizing shift in channel inactivation, thereby increasing the overlap of the activation and inactivation curves to increase window current. CONCLUSIONS Abnormal biophysical phenotypes implicate mutations in SNTA1 as a novel pathogenic mechanism for the subset of channelopathic SIDS. Functional studies are essential to distinguish pathogenic perturbations in channel interacting proteins such as alpha1-syntrophin from similarly rare but innocuous ones.

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With each cellular generation, oxygenic photoautotrophs must accumulate abundant protein complexes that mediate light capture, photosynthetic electron transport and carbon fixation. In addition to this net synthesis, oxygenic photoautotrophs must counter the light-dependent photoinactivation of Photosystem II (PSII), using metabolically expensive proteolysis, disassembly, resynthesis and re-assembly of protein subunits. We used growth rates, elemental analyses and protein quantitations to estimate the nitrogen (N) metabolism costs to both accumulate the photosynthetic system and to maintain PSII function in the diatom Thalassiosira pseudonana, growing at two pCO2 levels across a range of light levels. The photosynthetic system contains c. 15-25% of total cellular N. Under low growth light, N (re)cycling through PSII repair is only c. 1% of the cellular N assimilation rate. As growth light increases to inhibitory levels, N metabolite cycling through PSII repair increases to c. 14% of the cellular N assimilation rate. Cells growing under the assumed future 750 ppmv pCO2 show higher growth rates under optimal light, coinciding with a lowered N metabolic cost to maintain photosynthesis, but then suffer greater photoinhibition of growth under excess light, coincident with rising costs to maintain photosynthesis. We predict this quantitative trait response to light will vary across taxa.

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Tese de doutoramento, Sociologia (Sociologia da Família, Juventude e das Relações do Género), Universidade de Lisboa, Instituto de Ciências Sociais, 2016

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This paper examines the main EU-level initiatives that have been put forward in the weeks following the attacks in Paris in January 2015, which will be discussed in the informal European Council meeting of 12 February 2015. It argues that a majority of these proposals predated the Paris shootings and had until that point proved contentious as regards their efficacy, legitimacy and lawfulness. The paper finds that EU counterterrorism responses raise two fundamental challenges: A first challenge is posed to the freedom of movement, Schengen and EU citizenship. Priority is being given to the expanded use of large-scale surveillance and systematic monitoring of all travellers including EU citizens, which stands in contravention of Schengen and the free movement principle. A second challenge concerns EU democratic rule of law. Current pressures calling for the adoption of measures such as the EU Passenger Name Record challenge the scrutiny roles held by the European Parliament and the Court of Justice of the EU on counterterrorism measures in a post-Lisbon Treaty setting. The paper proposes that the EU adopts a new European Agenda on Security and Liberty based on an EU security (criminal justice-led) cooperation model that is firmly anchored in current EU legal principles and rule of law standards. This model would call for ‘less is more’ concerning the use, processing and retention of data by police and intelligence communities. Instead, it would pursue better and more accurate use of data meeting the quality standards of evidence in criminal judicial proceedings.

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This paper examines the EU’s counter-terrorism policies responding to the Paris attacks of 13 November 2015. It argues that these events call for a re-think of the current information-sharing and preventive-justice model guiding the EU’s counter-terrorism tools, along with security agencies such as Europol and Eurojust. Priority should be given to independently evaluating ‘what has worked’ and ‘what has not’ when it comes to police and criminal justice cooperation in the Union. Current EU counter-terrorism policies face two challenges: one is related to their efficiency and other concerns their legality. ‘More data’ without the necessary human resources, more effective cross-border operational cooperation and more trust between the law enforcement authorities of EU member states is not an efficient policy response. Large-scale surveillance and preventive justice techniques are also incompatible with the legal and judicial standards developed by the Court of Justice of the EU. The EU can bring further added value first, by boosting traditional policing and criminal justice cooperation to fight terrorism; second, by re-directing EU agencies’ competences towards more coordination and support in cross-border operational cooperation and joint investigations, subject to greater accountability checks (Europol and Eurojust +); and third, by improving the use of policy measures following a criminal justice-led cooperation model focused on improving cross-border joint investigations and the use of information that meets the quality standards of ‘evidence’ in criminal judicial proceedings. Any EU and national counter-terrorism policies must not undermine democratic rule of law, fundamental rights or the EU’s founding constitutional principles, such as the free movement of persons and the Schengen system. Otherwise, these policies will defeat their purpose by generating more insecurity, instability, mistrust and legal uncertainty for all.

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The improvement and performance of a micellar electrokinetic capillary chromatography assay for cefepime in human serum and plasma with a 50 μm id fused-silica capillary elongated from 40 to 60 cm is reported. Sample preparation with dodecylsulfate protein precipitation at pH 4.5, the pH 9.1 separation medium and the applied voltage were as reported previously[16]. The change resulted in a significant lower current, higher resolution and increased detection time intervals. The performance of the assay with multi-level internal calibration was assessed with calibration and control samples. Quality assurance data of a two year period assessed under the new conditions demonstrated the robustness of the assay. In serum samples of patients who received both cefepime and sulfamethoxazole, cefepime could not be detected due to the inseparability of the two compounds. The presence of an interference can be recognized by an increased peak width (width > 0.2 min), the appearance of a shoulder or an unresolved double peak. The patient data gathered during a three year period reveal that introduction of therapeutic drug monitoring led to a 50% reduction of the median drug level. The data suggest that therapeutic drug monitoring can help to minimize the risk of major adverse reactions and to increase drug safety on an individual basis. This article is protected by copyright. All rights reserved.

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Free drug measurement and pharmacodymanic markers provide the opportunity for a better understanding of drug efficacy and toxicity. High-performance liquid chromatography (HPLC)-mass spectrometry (MS) is a powerful analytical technique that could facilitate the measurement of free drug and these markers. Currently, there are very few published methods for the determination of free drug concentrations by HPLC-MS. The development of atmospheric pressure ionisation sources, together with on-line microdialysis or on-line equilibrium dialysis and column switching techniques have reduced sample run times and increased assay efficiency. The availability of such methods will aid in drug development and the clinical use of certain drugs, including anti-convulsants, anti-arrhythmics, immunosuppressants, local anaesthetics, anti-fungals and protease inhibitors. The history of free drug measurement and an overview of the current HPLC-MS applications for these drugs are discussed. Immunosuppressant drugs are used as an example for the application of HPLC-MS in the measurement of drug pharmacodynamics. Potential biomarkers of immunosuppression that could be measured by HPLC-MS include purine nucleoside/nucleotides, drug-protein complexes and phosphorylated peptides. At the proteomic level, two-dimensional gel electrophoresis combined with matrix-assisted laser desorption/ionisation time-of-flight (TOF) MS is a powerful tool for identifying proteins involved in the response to inflammatory mediators. (C) 2003 Elsevier Science B.V. All rights reserved.

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High-performance liquid chromatography coupled by an electrospray ion source to a tandem mass spectrometer (HPLC-EST-MS/ MS) is the current analytical method of choice for quantitation of analytes in biological matrices. With HPLC-ESI-MS/MS having the characteristics of high selectivity, sensitivity, and throughput, this technology is being increasingly used in the clinical laboratory. An important issue to be addressed in method development, validation, and routine use of HPLC-ESI-MS/MS is matrix effects. Matrix effects are the alteration of ionization efficiency by the presence of coeluting substances. These effects are unseen in the chromatograrn but have deleterious impact on methods accuracy and sensitivity. The two common ways to assess matrix effects are either by the postextraction addition method or the postcolumn infusion method. To remove or minimize matrix effects, modification to the sample extraction methodology and improved chromatographic separation must be performed. These two parameters are linked together and form the basis of developing a successful and robust quantitative HPLC-EST-MS/MS method. Due to the heterogenous nature of the population being studied, the variability of a method must be assessed in samples taken from a variety of subjects. In this paper, the major aspects of matrix effects are discussed with an approach to address matrix effects during method validation proposed. (c) 2004 The Canadian Society of Clinical Chemists. All rights reserved.