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991.
Kristoffersen L Øiestad EL Opdal MS Krogh M Lundanes E Christophersen AS 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》2007,850(1-2):147-160
A method for the simultaneous determination of the beta-blockers atenolol, sotalol, metoprolol, bisoprolol, propranolol and carvedilol, the calcium-channel antagonists diltiazem, amlodipine and verapamil, the angiotensin-II antagonists losartan, irbesartan, valsartan and telmisartan, and the antiarrhythmic drug flecainide, in whole blood samples from forensic autopsies was developed. Sample clean-up was achieved by precipitation and solid phase extraction (SPE) with a mixed-mode column. Quantification was performed by reversed phase high performance liquid chromatography with positive electrospray ionization mass spectrometric detection (HPLC-MS). The method has been developed and robustness tested by systematically searching for satisfactory conditions using experimental designs including factorial and response surface designs. With the exception of amlodipine, the concentration limit of quantification (cLOQ) covered low therapeutic concentration levels for all the compounds. Within assay precisions and accuracies (bias) were 3.4-21% RSD and from -24 to 21% for the concentration range 1.00-5.00 microM, respectively. Between assay precisions were 4.4-28% RSD for the concentration range from 0.1 to 5 microM and recoveries varied from 9 to 103%. The method is used for determination of cardiovascular drugs in post-mortem whole blood samples from forensic autopsy cases. 相似文献
992.
Peter Hammershøj Mikkel Jessing Anders Ø. Madsen Knud J. Jensen Jørn B. Christensen Ulrik Boas 《International journal of peptide research and therapeutics》2007,13(1-2):209-212
The development of new linkers (handles) for solid-phase synthesis provides new chemical opportunities for peptide synthesis.
To understand the chemical properties of a recently developed backbone amide linker from a structural perspective, the crystal
structure of S-((5-formyl-3,4-ethylenedioxy)thiophene-2-yl)-3-thiopropionic acid (T-BAL2) was studied. Specifically, we wished
to address whether this highly substituted thiophene retained planarity in the aromatic ring as well as between the aromatic
ring and the aldehyde carbonyl. Furthermore, we sought an explanation for the relatively low reactivity in reductive aminations
of the thienylaldehyde with amines in solution and on solid phase. Based on the crystal structure of T-BAL2, the thienyl-C
(aldehyde) and C–O (aldehyde) bond lengths were applied as measures for the electron-deficiency (electrophilicity) of the
aldehyde and compared to similar bond lengths found in previously reported formylated homo- and hetero-aromatic systems, which
show significantly higher reactivity towards imine formation. The bond lengths found in the present structure are in accordance
with normal C–C single bond and C–O double bond lengths. The high similarity in aldehyde bond lengths in the present system
and in the reported systems indicates similar electron distribution in these systems. The lower reactivity of the present
system may therefore not be attributed to electronic factors. 相似文献
993.
Michael Adsetts Edberg Hansen Jørn Smedsgaard 《Metabolomics : Official journal of the Metabolomic Society》2007,3(1):41-54
The use of mass spectrometry (MS) is pivotal in analyses of the metabolome and presents a major challenge for subsequent data
processing. While the last few years have given new high performance instruments, there has not been a comparable development
in data processing. In this paper we discuss an automated data processing pipeline to compare large numbers of fingerprint
spectra from direct infusion experiments analyzed by high resolution MS. We describe some of the intriguing problems that
have to be addressed, starting with the conversion and pre-processing of the raw data to the final data analysis. Illustrated
on the direct infusion analysis (ESI-TOF-MS) of complex mixtures the method exploits the full quality of the high-resolution
present in the mass spectra. Although the method is illustrated as a new library search method for high resolution MS, we
demonstrate that the output of the preprocessing is applicable to cluster-, discriminant analysis, and related multivariate
methods applied directly to mass spectra from direct infusion analysis of crude extracts. This is done to find the relationship
between several terverticillate Penicillium species and identify the ions responsible for the segregation. 相似文献
994.
Spatial, temporal, and species variation in prevalence of influenza A viruses in wild migratory birds 总被引:2,自引:0,他引:2
Munster VJ Baas C Lexmond P Waldenström J Wallensten A Fransson T Rimmelzwaan GF Beyer WE Schutten M Olsen B Osterhaus AD Fouchier RA 《PLoS pathogens》2007,3(5):e61
Although extensive data exist on avian influenza in wild birds in North America, limited information is available from elsewhere, including Europe. Here, molecular diagnostic tools were employed for high-throughput surveillance of migratory birds, as an alternative to classical labor-intensive methods of virus isolation in eggs. This study included 36,809 samples from 323 bird species belonging to 18 orders, of which only 25 species of three orders were positive for influenza A virus. Information on species, locations, and timing is provided for all samples tested. Seven previously unknown host species for avian influenza virus were identified: barnacle goose, bean goose, brent goose, pink-footed goose, bewick's swan, common gull, and guillemot. Dabbling ducks were more frequently infected than other ducks and Anseriformes; this distinction was probably related to bird behavior rather than population sizes. Waders did not appear to play a role in the epidemiology of avian influenza in Europe, in contrast to the Americas. The high virus prevalence in ducks in Europe in spring as compared with North America could explain the differences in virus-host ecology between these continents. Most influenza A virus subtypes were detected in ducks, but H13 and H16 subtypes were detected primarily in gulls. Viruses of subtype H6 were more promiscuous in host range than other subtypes. Temporal and spatial variation in influenza virus prevalence in wild birds was observed, with influenza A virus prevalence varying by sampling location; this is probably related to migration patterns from northeast to southwest and a higher prevalence farther north along the flyways. We discuss the ecology and epidemiology of avian influenza A virus in wild birds in relation to host ecology and compare our results with published studies. These data are useful for designing new surveillance programs and are particularly relevant due to increased interest in avian influenza in wild birds. 相似文献
995.
996.
Using likelihood-free inference to compare evolutionary dynamics of the protein networks of H. pylori and P. falciparum
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Ratmann O Jørgensen O Hinkley T Stumpf M Richardson S Wiuf C 《PLoS computational biology》2007,3(11):e230
Gene duplication with subsequent interaction divergence is one of the primary driving forces in the evolution of genetic systems. Yet little is known about the precise mechanisms and the role of duplication divergence in the evolution of protein networks from the prokaryote and eukaryote domains. We developed a novel, model-based approach for Bayesian inference on biological network data that centres on approximate Bayesian computation, or likelihood-free inference. Instead of computing the intractable likelihood of the protein network topology, our method summarizes key features of the network and, based on these, uses a MCMC algorithm to approximate the posterior distribution of the model parameters. This allowed us to reliably fit a flexible mixture model that captures hallmarks of evolution by gene duplication and subfunctionalization to protein interaction network data of Helicobacter pylori and Plasmodium falciparum. The 80% credible intervals for the duplication–divergence component are [0.64, 0.98] for H. pylori and [0.87, 0.99] for P. falciparum. The remaining parameter estimates are not inconsistent with sequence data. An extensive sensitivity analysis showed that incompleteness of PIN data does not largely affect the analysis of models of protein network evolution, and that the degree sequence alone barely captures the evolutionary footprints of protein networks relative to other statistics. Our likelihood-free inference approach enables a fully Bayesian analysis of a complex and highly stochastic system that is otherwise intractable at present. Modelling the evolutionary history of PIN data, it transpires that only the simultaneous analysis of several global aspects of protein networks enables credible and consistent inference to be made from available datasets. Our results indicate that gene duplication has played a larger part in the network evolution of the eukaryote than in the prokaryote, and suggests that single gene duplications with immediate divergence alone may explain more than 60% of biological network data in both domains. 相似文献
997.
The Hardangervidda in southern Norway, the largest mountain plateau in Europe, has thousands of lakes and streams, mainly
between 1000 and 1300 m above sea level, where brown trout is the only fish species. To describe the current genetic diversity
of brown trout in this area, a total of 863 fish from 20 lakes were genotyped with eleven microsatellites. Most diversity
is within lake populations, but diversity among geographical groups and populations within groups was significant, too. Neighbor-joining,
principle coordinate analysis and Bayesian clustering show three major geographic groups in accordance with the river systems.
Bias was caused by recent stocking in two lakes. Low/no genetic differentiation among some populations indicates that intermixing
is common when lakes are well-connected, as was also shown by assignment test. We recommend preserving the genetic diversity
of brown trout in this unique area by managing stocking in lake systems according to genetic structure. 相似文献
998.
Jon-Ivar Westgaard Tekle Tafese Mette Serine Wesmajervi Frank Nilsen Kjersti Turid Fjalestad Børge Damsgård Madjid Delghandi 《Conservation Genetics》2007,8(6):1503-1506
Ten polymorphic microsatellite markers were developed from approximately 1,300 expressed sequence tags (ESTs) of Atlantic
cod (Gadus morhua L.). Thirty two primer pairs were designed for EST sequences containing perfect di- tri- tetra- and pentanucleotide motifs
and characterised in 96 unrelated fish. Ten markers were successfully amplified with number of alleles from 2 to 13 per locus
and observed and expected heterozygosity ranging from 0.03 to 0.69 and 0.03 to 0.74, respectively. Loci Gmo-C131, C132 and C136 deviated from Hardy-Weinberg equilibrium. Genetic linkage disequilibrium analysis between all pairs of
the loci showed significant departure from the null hypothesis between loci Gmo-C131 and Gmo-C132 and C128 and Gmo-C133. The gene identity was determined at five of the loci, confirming the associated microsatellites as Type I markers.
The new microsatellites reported in this work can be used for conservation and enhancement of wild stocks for commercial harvesting.
Jon-Ivar Westgaard and Tekle Tafese have contributed equally to the work. 相似文献
999.
1000.
Strengthening the Reporting of Observational Studies in Epidemiology (STROBE): explanation and elaboration 总被引:1,自引:0,他引:1
Vandenbroucke JP von Elm E Altman DG Gøtzsche PC Mulrow CD Pocock SJ Poole C Schlesselman JJ Egger M;STROBE Initiative 《PLoS medicine》2007,4(10):e297
Much medical research is observational. The reporting of observational studies is often of insufficient quality. Poor reporting hampers the assessment of the strengths and weaknesses of a study and the generalisability of its results. Taking into account empirical evidence and theoretical considerations, a group of methodologists, researchers, and editors developed the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) recommendations to improve the quality of reporting of observational studies. The STROBE Statement consists of a checklist of 22 items, which relate to the title, abstract, introduction, methods, results and discussion sections of articles. Eighteen items are common to cohort studies, case-control studies and cross-sectional studies and four are specific to each of the three study designs. The STROBE Statement provides guidance to authors about how to improve the reporting of observational studies and facilitates critical appraisal and interpretation of studies by reviewers, journal editors and readers. This explanatory and elaboration document is intended to enhance the use, understanding, and dissemination of the STROBE Statement. The meaning and rationale for each checklist item are presented. For each item, one or several published examples and, where possible, references to relevant empirical studies and methodological literature are provided. Examples of useful flow diagrams are also included. The STROBE Statement, this document, and the associated Web site (http://www.strobe-statement.org/) should be helpful resources to improve reporting of observational research. 相似文献