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Recent Methods (recent + methods)
Selected AbstractsSatellite DNA and chromosomes in Neotropical fishes: methods, applications and perspectivesJOURNAL OF FISH BIOLOGY, Issue 5 2010M. R. Vicari Constitutive heterochromatin represents a substantial portion of the eukaryote genome, and it is mainly composed of tandemly repeated DNA sequences, such as satellite DNAs, which are also enriched by other dispersed repeated elements, including transposons. Studies on the organization, structure, composition and in situ localization of satellite DNAs have led to consistent advances in the understanding of the genome evolution of species, with a particular focus on heterochromatic domains, the diversification of heteromorphic sex chromosomes and the origin and maintenance of B chromosomes. Satellite DNAs can be chromosome specific or species specific, or they can characterize different species from a genus, family or even representatives of a given order. In some cases, the presence of these repeated elements in members of a single clade has enabled inferences of a phylogenetic nature. Genomic DNA restriction, using specific enzymes, is the most frequently used method for isolating satellite DNAs. Recent methods such as C0t,1 DNA and chromosome microdissection, however, have proven to be efficient alternatives for the study of this class of DNA. Neotropical ichthyofauna is extremely rich and diverse enabling multiple approaches with regard to the differentiation and evolution of the genome. Genome components of some species and genera have been isolated, mapped and correlated with possible functions and structures of the chromosomes. The 5SHindIII-DNA satellite DNA, which is specific to Hoplias malabaricus of the Erythrinidae family, has an exclusively centromeric location. The As51 satellite DNA, which is closely correlated with the genome diversification of some species from the genus Astyanax, has also been used to infer relationships between species. In the Prochilodontidae family, two repetitive DNA sequences were mapped on the chromosomes, and the SATH 1 satellite DNA is associated with the origin of heterochromatic B chromosomes in Prochilodus lineatus. Among species of the genus Characidium and the Parodontidae family, amplifications of satellite DNAs have demonstrated that these sequences are related to the differentiation of heteromorphic sex chromosomes. The possible elimination of satellite DNA units could explain the genome compaction that occurs among some species of Neotropical Tetraodontiformes. These topics are discussed in the present review, showing the importance of satellite DNA analysis in the differentiation and karyotype evolution of Actinopterygii. [source] Perfusion MRI with radial acquisition for arterial input function assessment,MAGNETIC RESONANCE IN MEDICINE, Issue 5 2007Eugene G. Kholmovski Abstract Quantification of myocardial perfusion critically depends on accurate arterial input function (AIF) and tissue enhancement curves (TECs). Except at low doses, the AIF is inaccurate because of the long saturation recovery time (SRT) of the pulse sequence. The choice of dose and SRT involves a trade-off between the accuracy of the AIF and the signal-to-noise ratio (SNR) of the TEC. Recent methods to resolve this trade-off are based on the acquisition of two data sets: one to accurately estimate the AIF, and one to find the high-SNR TEC. With radial k -space sampling, a set of images with varied SRTs can be reconstructed from the same data set, allowing an accurate assessment of the AIF and TECs, and their conversion to contrast agent (CA) concentration. This study demonstrates the feasibility of using a radial acquisition for quantitative myocardial perfusion imaging. Magn Reson Med 57:821,827, 2007. © 2007 Wiley-Liss, Inc. [source] ASSESSING CURRENT ADAPTATION AND PHYLOGENETIC INERTIA AS EXPLANATIONS OF TRAIT EVOLUTION:THE NEED FOR CONTROLLED COMPARISONSEVOLUTION, Issue 10 2005Thomas F. Hansen Abstract The determination of whether the pattern of trait evolution observed in a comparative analysis of species data is due to adaptation to current environments, to phylogenetic inertia, or to both of these forces requires that one control for the effects of either force when making an assessment of the evolutionary role of the other. Orzack and Sober (2001) developed the method of controlled comparisons to make such assessments; their implementation of the method focussed on a discretely varying trait. Here, we show that the method of controlled comparisons can be viewed as a meta-method, which can be implemented in many ways. We discuss which recent methods for the comparative analysis of continuously distributed traits can generate controlled comparisons and can thereby be used to properly assess whether current adaptation and/or phylogenetic inertia have influenced a trait's evolution. The implementation of controlled comparisons is illustrated by an analysis of sex-ratio data for fig wasps. This analysis suggests that current adaptation and phylogenetic inertia influence this trait. [source] A brief introduction to cell-penetrating peptidesJOURNAL OF MOLECULAR RECOGNITION, Issue 5 2003Pontus Lundberg Abstract Cell membranes act as protective walls to exclude most molecules that are not actively imported by living cells. This is an efficient way for a cell to prevent uncontrolled influx or efflux of solutes, which otherwise would be harmful to it. Only compounds within a narrow range of molecular size, polarity and net charge are able to diffuse effectively through cell membranes. In order to overcome this barrier for effective delivery of membrane-impermeable molecules, several chemical and physical methods have been developed. These methods, e.g. electroporation, and more recent methods as cationic lipids/liposomes, have been shown to be effective for delivering hydrophobic macromolecules. The drawbacks of these harsh methods are, primarily, the unwanted cellular effects exerted by them, and, secondly, their limitation to in vitro applications. The last decade's discovery of cell-penetrating peptides translocating themselves across cell membranes of various cell lines, along with a cargo 100-fold their own size, via a seemingly energy-independent process, opens up the possibility for efficient delivery of DNA, antisense peptide nucleic acids, oligonucleotides, proteins and small molecules into cells both in vitro and in vivo. Copyright © 2003 John Wiley & Sons, Ltd. [source] Personality Over Time: Methodological Approaches to the Study of Short-Term and Long-Term Development and ChangeJOURNAL OF PERSONALITY, Issue 6 2003Jeremy C. Biesanz We consider a variety of recent methods of longitudinal data analysis to examine both short-term and long-term development and change in personality, including mean-level analyses both across and within individuals across time, variance structures across time, and cycles and dynamic models across time. These different longitudinal analyses can address classic as well as new questions in the study of personality and its development. We discuss the linkages among different longitudinal analyses, measurement issues in temporal data, the spacing of assessments, and the levels of generalization and potential insights afforded by different longitudinal analyses. [source] Analysis of solid-state transformations of pharmaceutical compounds using vibrational spectroscopyJOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 8 2009Andrea Heinz Abstract Objectives Solid-state transformations may occur during any stage of pharmaceutical processing and upon storage of a solid dosage form. Early detection and quantification of these transformations during the manufacture of solid dosage forms is important since the physical form of an active pharmaceutical ingredient can significantly influence its processing behaviour, including powder flow and compressibility, and biopharmaceutical properties such as solubility, dissolution rate and bioavailability. Key findings Vibrational spectroscopic techniques such as infrared, near-infrared, Raman and, most recently, terahertz pulsed spectroscopy have become popular for solidstate analysis since they are fast and non-destructive and allow solid-state changes to be probed at the molecular level. In particular, Raman and near-infrared spectroscopy, which require no sample preparation, are now commonly used coupled to fibreoptic probes and are able to characterise solid-state conversions in-line. Traditionally, uni- or bivariate approaches have been used to analyse spectroscopic data sets; however, recently the simultaneous detection of several solid-state forms has been increasingly performed using multivariate approaches where even overlapping spectral bands can be analysed. Summary This review discusses the applications of different vibrational spectroscopic techniques to detect and monitor solid-state transformations possible for crystalline polymorphs, hydrates and amorphous forms of pharmaceutical compounds. In this context, the theoretical basis of solid-state transformations and vibrational spectroscopy and common experimental approaches are described, including recent methods of data analysis. [source] Pathogen-induced resistance and alarm signals in the phloemMOLECULAR PLANT PATHOLOGY, Issue 5 2004AART J. E. VAN BEL SUMMARY Despite a long-standing notion of long-distance signals triggering systemic acquired resistance (SAR), the translocation pathway and the identity of the signals involved have not been determined with any degree of certainty. A critical assessment indicates that, in parallel to signalling via the phloem, alternative modes for SAR induction such as signalling via the xylem or air-borne signalling by volatile substances may occur. This review further evaluates several classes of compounds as being functional in systemic resistance signalling. Evidence in favour of SAR involvement of phloem-mobile substances such as salicylic acid, lipid-derived molecules, reactive oxygen species and components of the antioxidant machinery is contradictory, circumstantial or inconclusive, at best. Nitric oxide bound to proteins or thiols seems a good candidate for signalling, but has not been found in phloem sap thus far. No convincing support of the involvement in SAR of phloem-mobile substances such as calcium, oligosaccharides, peptides or RNA species, which function in other systemic signalling cascades, has yet been produced. Nevertheless, phloem-mobile macromolecules are considered as potential tools for SAR given their pivotal role in remote gene expression under stress conditions. In this framework, the existence of several cascades for signal generation along the phloem pathway is envisaged. Finally, recent methods for detection of molecular signals in phloem sap and their expression in companion cells are presented. [source] Opportunities afforded by the study of unmyelinated nerves in skin and other organsMUSCLE AND NERVE, Issue 6 2004William R. Kennedy MS Abstract Neurological practice is mainly focused on signs and symptoms of disorders that involve functions governed by myelinated nerves. Functions controlled by unmyelinated nerve fibers have necessarily remained in the background because of the inability to consistently stain, image, or construct clinically applicable neurophysiological tests of these nerves. The situation has changed with the introduction of immunohistochemical methods and confocal microscopy into clinical medicine, as these provide clear images of thin unmyelinated nerves in most organs. One obvious sign of change is the increasing number of reports from several laboratories of the pathological alterations of cutaneous nerves in skin biopsies from patients with a variety of clinical conditions. This study reviews recent methods to stain and image unmyelinated nerves as well as the use of these methods for diagnosing peripheral neuropathy, for experimental studies of denervation and reinnervation in human subjects, and for demonstrating the vast array of unmyelinated nerves in internal organs. The new ability to examine the great variety of nerves in different organs opens opportunities and creates challenges and responsibilities for neurologists and neuroscientists. Muscle Nerve 756,767, 2004 [source] Baroreflex Sensitivity: Measurement and Clinical ImplicationsANNALS OF NONINVASIVE ELECTROCARDIOLOGY, Issue 2 2008Maria Teresa La Rovere M.D. Alterations of the baroreceptor-heart rate reflex (baroreflex sensitivity, BRS) contribute to the reciprocal reduction of parasympathetic activity and increase of sympathetic activity that accompany the development and progression of cardiovascular diseases. Therefore, the measurement of the baroreflex is a source of valuable information in the clinical management of cardiac disease patients, particularly in risk stratification. This article briefly recalls the pathophysiological background of baroreflex control, and reviews the most relevant methods that have been developed so far for the measurement of BRS. They include three "classic" methods: (i) the use of vasoactive drugs, particularly the ,-adrenoreceptor agonist phenylephrine, (ii) the Valsalva maneuver, which produces a natural challenge for the baroreceptors by voluntarily increasing intrathoracic and abdominal pressure through straining, and (iii) the neck chamber technique, which allows a selective activation/deactivation of carotid baroreceptors by application of a negative/positive pressure to the neck region. Two more recent methods based on the analysis of spontaneous oscillations of systolic arterial pressure and RR interval are also reviewed: (i) the sequence method, which analyzes the relationship between increasing/decreasing ramps of blood pressure and related increasing/decreasing changes in RR interval through linear regression, and (ii) spectral methods, which assess the relationship (in terms of gain) between specific oscillatory components of the two signals. The limitations of the coherence criterion for the computation of spectral BRS are discussed, and recent proposals for overcoming them are presented. Most relevant clinical applications of BRS measurement are finally reviewed with particular reference to patients with myocardial infarction and heart failure. [source] High-performance liquid chromatography coupled with mass spectrometry for the quantitative analysis of vinca-alkaloids in biological matrices: a concise survey from the literatureBIOMEDICAL CHROMATOGRAPHY, Issue 1 2010Carola W. N. Damen Abstract The bioanalysis of vinca-alkaloids has been investigated extensively. High-performance liquid chromatography coupled to ultraviolet, fluorescence or electrochemical detection have been described. During recent years liquid chromato-graphy coupled with mass spectrometry (LC-MS) has become the first choice for the quantitative bioanalysis of the vinca anticancer agents. This paper reviews recent methods for the bio-analysis of vinca-alkaloids using LC-MS, supplemented with our own experience. We will focus on sample pre-treatment, chromatography and MS detection and pay attention to problems which can occur during the bioanalysis of vinca-alkaloids. These problems encounter carry-over and absorption effects and solutions will be provided how to circumvent these problems. Copyright © 2009 John Wiley & Sons, Ltd. [source] Evaluation of quality of life, and priorities in people with glaucomaACTA OPHTHALMOLOGICA, Issue 2009P ASPINALL Purpose Quality of life appears to be of increasing importance as a criterion for clinical intervention. However its meaning can be complex and its assessment varied. In social science the term has broad definitions which include terms such as autonomy, wellbeing; self esteem; sense of control etc. On the other hand within ophthalmology a narrower operational definition is mainly used which is the degree to which someone's vision impacts on a range of necessary and desirable daily tasks a person wishes to carry out. The purpose of the presentation is to compare alternative methods of quality of life assessment. Methods The assessment approaches taken in the study range from conventional questionnaire rating scales, (something NICE has questioned) and time trade off comparisons, to more recent methods of scaling generated by for example Rasch or Hierarchical Bayesian analysis. Results Data will be presented from two studies (one in Edinburgh and one in Aberdeen) on quality of life in people with glaucoma. One of the new recommended discrete choice methods (Choice based conjoint analysis with Hierarchical Bayesian estimates) will be used. The results will include quality of life outcomes and their stability; related visual factors; comparisons across methods and more general implications for quality of life assessment. Conclusion Different methods for the assessment of quality of life produce different results with relatively low correlations between them although conjoint analysis has revealed stable priorities across two independent studies. These discrepancies in quality of life assessment require further study and evaluation. [source] High-throughput epidemiologic typing in clinical microbiologyCLINICAL MICROBIOLOGY AND INFECTION, Issue 2 2003A. Van Belkum Mapping, and ultimately preventing, the dissemination of infectious agents is an important topic in public health. Newly developed molecular,microbiological methods have contributed significantly to recent advances in the efficient tracking of the nosocomial and environmental spread of microbial pathogens. Not only has the application of novel technologies led to improved understanding of microbial epidemiology, but the concepts of population structure and dynamics of many of the medically significant microorganisms have advanced significantly also. Currently, genetic identification of microbes is also within the reach of clinical microbiology laboratory professionals including those without specialized technology research interests. This review summarizes the possibilities for high-throughput molecular,microbiological typing in adequately equipped medical microbiology laboratories from both clinical and fundamental research perspectives. First, the development and application of methods for large-scale comparative typing of serially isolated microbial strains are discussed. The outcome of studies employing these methods allows for long-term epidemiologic surveillance of infectious diseases. Second, recent methods enable an almost nucleotide-by-nucleotide genetic comparison of smaller numbers of strains, thereby facilitating the identification of the genetic basis of, for instance, medically relevant microbiological traits. Whereas the first approach provides insights into the dynamic spread of infectious agents, the second provides insights into intragenomic dynamics and genetic functionality. The current state of technology is summarized, and future perspectives are sketched. [source] | ||||||||||||||||