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Analytical Developments (analytical + development)
Selected AbstractsIn vivo simultaneous monitoring of ,-aminobutyric acid, glutamate, and L -aspartate using brain microdialysis and capillary electrophoresis with laser-induced fluorescence detection: Analytical developments and in vitro/in vivo validationsELECTROPHORESIS, Issue 18 2003Valérie Sauvinet Abstract ,-Aminobutyric acid (GABA), glutamate (Glu), and L -aspartate (L -Asp) are three major amino acid neurotransmitters in the central nervous system. In this work, a method for the separation of these three neurotransmitters in brain microdialysis samples using a commercially available capillary electrophoresis (CE) system has been developed. Molecules were tagged on their primary amine function with the fluorogene agent naphthalene-2,3-dicarboxaldehyde (NDA), and, after separation by micellar electrokinetic chromatography, were detected by laser-induced fluorescence using a 442 nm helium-cadmium laser. The separation conditions for the analysis of derivatized neurotransmitters in standard solutions and microdialysates have been optimized, and this method has been validated on both pharmacological and analytical basis. The separation of GABA, Glu, and L -Asp takes less than 10 min by using a 75 mmol/L borate buffer, pH 9.2, containing 70 mmol/L SDS and 10 mmol/L hydroxypropyl-,-cyclodextrin and +,25 kV voltage. The detection limits were 3, 15 nmol/L and, 5 nmol/L for GABA, Glu, and L -Asp, respectively. Moreover, submicroliter samples can be analyzed. This method allows a simple, rapid and accurate measurement of the three amino acid neurotransmitters for the in vivo brain monitoring using microdialysis sampling. [source] Biochemical and analytical development of the CIME cocktail for drug fate assessment in humansRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 16 2010Orianne Videau Phenotyping based on drug metabolism activity appears to be informative regarding mechanism-based interactions during drug development. We report here the first steps of the development of the innovative CIME cocktail. This cocktail is designed not only for the major cytochrome P450, with caffeine, amodiaquine, tolbutamide, omeprazole, dextromethorphan and midazolam as substrates of CYP1A2, CYP2C8, CYP2C9, CYP2C19, CYP2D6 and CYP3A, respectively, but also phase II enzymes UGT 1A1/6/9 with acetaminophen, P-gp and OATP1B1 with digoxin and rosuvastatin, and renal function with memantine. An assay combining ultra-performance liquid chromatography using a 1.7,µm particle size column with tandem mass spectrometry (UPLC/MS/MS) was set up for the simultaneous quantification of the 20 substrates and metabolites after extraction from human plasma using solid-phase extraction. The method was validated in the spirit of the FDA guidelines. Mean accuracy ranged from 87.7 to 115%, the coefficient of variance (CV%) of intra- and inter-run from 1.7 to 16.4% and from 1.6 to 14.9%, respectively, and for the limit of quantification (LOQ) with ten lots of plasma, accuracy ranged from 84 to 115% and CV% precision was <16%. Short-term stability was evaluated in eluate (4,h, room temperature), plasma (24,h, room temperature), the autosampler (24,h, 4°C) and in three freeze/thaw cycles in plasma. All except three analytes were stable under these conditions. For the three others a specific process can be followed. This robust, fast and sensitive assay in human plasma provides an analytical tool for ten-probe drugs of the CIME cocktail. Clinical samples will be assayed in the near future using this new assay method. Copyright © 2010 John Wiley & Sons, Ltd. [source] Recent Developments in Trace Element Analysis by ICP-AES and ICP-MS with Particular Reference to Geological and Environmental SamplesGEOSTANDARDS & GEOANALYTICAL RESEARCH, Issue 1 2005Kathryn L. Linge This review describes recent developments in trace element analysis using inductively coupled plasma-atomic emission spectrometry (ICP-AES) and inductively coupled plasma-mass spectrometry (ICP-MS). It aims to focus on the application of ICP techniques to geological and environmental samples. Therefore, fundamental studies in ICP-MS and ICP-AES instrumentation have largely been ignored. Whereas the majority of literature reviewed related to ICP-MS, indicating that ICP-MS is now the preferred technique for all geological analysis, there is still a steady development of ICP-AES to environmental applications. It is clear that true flexibility in elemental analysis can only be achieved by combining the advantages of both ICP-AES and ICP-MS. Two particular groups of elements (long-lived radionuclide and the platinum-group elements) stood out as warranting dedicated sections describing analytical developments these areas. [source] Macroecology, global change and the shadow of forgotten ancestorsGLOBAL ECOLOGY, Issue 1 2008José Alexandre Felizola Diniz-Filho ABSTRACT Many recent studies have evaluated how global changes will affect biodiversity, and have mainly focused on how to develop conservation strategies to avoid, or at least minimize, extinctions due to shifts in suitable habitats for the species. However, these complex potential responses might be in part structured in phylogeny, because of the macroecological traits underlying them. In this comment, we review recent analytical developments in phylogenetic comparative methods that can be used to understand patterns of trait changes under environmental change. We focus on a partial regression approach that allows for partitioning the variance of traits into a fraction attributed to a pure ecological component, a fraction attributed to phylogenetically structured environmental variation (niche conservatism) and a fraction that may be attributed to phylogenetic effects only. We then develop a novel interpretation for linking these components for multiple traits with potential responses of species to global environmental change (i.e. adaptation, range shifts or extinctions). We hope that this interpretation will stimulate further research linking evolutionary components of multiple traits with broad-scale environmental changes. [source] Homoplasy and mutation model at microsatellite loci and their consequences for population genetics analysisMOLECULAR ECOLOGY, Issue 9 2002Arnaud Estoup Abstract Homoplasy has recently attracted the attention of population geneticists, as a consequence of the popularity of highly variable stepwise mutating markers such as microsatellites. Microsatellite alleles generally refer to DNA fragments of different size (electromorphs). Electromorphs are identical in state (i.e. have identical size), but are not necessarily identical by descent due to convergent mutation(s). Homoplasy occurring at microsatellites is thus referred to as size homoplasy. Using new analytical developments and computer simulations, we first evaluate the effect of the mutation rate, the mutation model, the effective population size and the time of divergence between populations on size homoplasy at the within and between population levels. We then review the few experimental studies that used various molecular techniques to detect size homoplasious events at some microsatellite loci. The relationship between this molecularly accessible size homoplasy size and the actual amount of size homoplasy is not trivial, the former being considerably influenced by the molecular structure of microsatellite core sequences. In a third section, we show that homoplasy at microsatellite electromorphs does not represent a significant problem for many types of population genetics analyses realized by molecular ecologists, the large amount of variability at microsatellite loci often compensating for their homoplasious evolution. The situations where size homoplasy may be more problematic involve high mutation rates and large population sizes together with strong allele size constraints. [source] | ||||||||||