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Various Approaches (various + approach)
Selected AbstractsSummary of contributions to GAW15 Group 16: Processing/normalization of expression traitsGENETIC EPIDEMIOLOGY, Issue S1 2007Aurélie Labbe Abstract Here, we summarize the contributions to group 16 of Genetic Analysis Workshop 15, held in Florida, U.S.A. The theme of this group was preprocessing of expression quantitative trait loci (eQTL) studies using the Affymetrix platform. The objective of the Genetic Analysis Workshop 15 problem 1 dataset was to use transcript levels that are measured using DNA microarrays as quantitative traits and localize the genes or other features of the DNA that control gene expression by quantitative trait loci linkage analyses. All contributors of this group used the microarray expression profiles (problem 1) data. Various approaches and questions were examined to investigate the effects of preprocessing methods and/or gene filtering on the interpretation of data, specifically on heritability estimates of gene expression and on linkage results. In addition, some contributors focused on the statistical issues involved in large-scale genetic analyses of quantitative traits that account for or build composite phenotypes from a large number of correlated traits. Since the true eQTLs are not known in the problem 1 data, results from the 11 studies cannot be fully evaluated for the methods employed. However, several common trends were found. All reports concluded that preprocessing statistical analyses may have an important impact on eQTL analyses and on the identification of cis -/trans -regulators and/or major biological pathways. Genet. Epidemiol. 31(Suppl. 1):S132,S138, 2007. © 2007 Wiley-Liss, Inc. [source] The management of inhibitors in haemophilia A: introduction and systematic review of current practiceHAEMOPHILIA, Issue 4 2003S. Paisley Summary., Haemophilia is the commonest bleeding disorder in the UK, affecting approximately 5400 people, almost all of them male. In haemophiliacs, reduced levels, or absence, of factor VIII (FVIII) cause bleeding episodes, typically into joint spaces or muscles. Haemophilia is generally treated with exogenous FVIII. However, in some haemophiliacs, therapeutically administered FVIII comes to be recognized as a foreign protein, stimulating the production of antibodies (inhibitors), which react with FVIII to render it ineffective. Alternative treatment strategies then have to be used to manage bleeding episodes. In addition, strategies have been developed to attempt to abolish inhibitor production through the induction of immune tolerance. A systematic review was undertaken of current international practice for the clinical management of haemophilia A patients with inhibitors to FVIII, concentrating on literature published from 1995 onwards. Although it can be difficult to determine what constitutes current practice, current guidelines indicate that immune tolerance induction is seen as desirable, with the choice of regimen dependent on patient characteristics, familiarity with regimens and cost. Various approaches, based on similar factors, are used to control bleeding episodes. [source] The phylogenetic origins of the antigen-binding receptors and somatic diversification mechanismsIMMUNOLOGICAL REVIEWS, Issue 1 2004John P. Cannon Summary:, The adaptive immune system arose in ancestors of the jawed vertebrates approximately 500 million years ago. Homologs of immunoglobulins (Igs), T-cell antigen receptors (TCRs), major histocompatibility complex I (MHC I) and MHC II, and the recombination-activating genes (RAGs) have been identified in all extant classes of jawed vertebrates; however, no definitive homolog of any of these genes has been identified in jawless vertebrates or invertebrates. RAG-mediated recombination and associated junctional diversification of both Ig and TCR genes occurs in all jawed vertebrates. In the case of Igs, somatic variation is expanded further through class switching, gene conversion, and somatic hypermutation. Although the identity of the ,primordial' receptor that was interrupted by the recombination mechanism in jawed vertebrates may never be established, many different families of genes that exhibit predicted characteristics of such a receptor have been described both within and outside the jawed vertebrates. Recent data from various model systems point toward a continuum of immune receptor diversity, encompassing many different families of recognition molecules whose functions are integrated in an organism's response to pathogenic invasion. Various approaches, including both genomic and protein-functional analyses, currently are being applied in jawless vertebrates, protochordates, and other invertebrate deuterostome systems and may yield definitive evidence regarding the presence or absence of adaptive immune homologs in species lacking adaptive immune systems. Such studies have the potential for uncovering previously unknown mechanisms of generating receptor diversity. [source] Bone regeneration in rabbit sinus lifting associated with bovine BMPJOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 2 2004Sergio Allegrini Jr. Abstract Autogenous bone is considered the optimal grafting material for sinus lifting, although its harvesting causes great patient discomfort. Various approaches have been taken in order to obtain sinus lifting with preexisting tissue. However, because of the unsuitability of such tissue, additional materials have been required. Alternatively, biomaterials from humans or other animals are used. In this study, the efficacy of using morphogenetic bovine bone protein (BMPb) to augment the maxillary sinus floor was examined. Four grafting materials were employed: lyophilized bovine bone powder, absorbable collagen flakes, natural hydroxylapatite, and synthetic hydroxylapatite. Two groups of rabbits were studied. In one group, graft material only was used. In the other, graft material was combined with 0.5 mg BMPb. During 8 weeks of observation, polyfluorochrome tracers were injected in subcutaneous tissue to evaluate new bone- deposition periods. Following sacrifice, the samples were examined under fluorescent and light microscopes. Results indicated 33.34% more newly formed bone in BMPb animals than in controls. Graft-material resorption increased, but natural HA showed no significant alterations. The results show that the use of BMPb, although providing osteoinduction, might not promote sufficient bone formation. Nonetheless, this material could provide an alternative to autogenous grafts, thereby avoiding patient discomfort. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 68B: 127,131, 2004 [source] Preparation of tritium-labelled BIIL 260 of high specific radioactivityJOURNAL OF LABELLED COMPOUNDS AND RADIOPHARMACEUTICALS, Issue 3 2003V.P. Shevchenko Abstract Various approaches to the synthesis of tritium-labelled BIIL 260 with high specific radioactivity were investigated. Attempts to incorporate tritium directly into BIIL 260 were made by solid-phase isotope exchange with tritium gas and by isotope exchange with tritiated water which yielded a final product with specific activities ranging from 2 to 7 Ci/mmol. However, the solid-phase and liquid-phase dehalogenations of an appropriate synthon fragment of BIIL 260 followed by its subsequent conversion to the final product via chemical synthesis yielded the desired tritium-labelled BIIL 260 with specific activities of 25 or 71 Ci/mmol, depending upon the precursors and methods used in the dehalogenation step. Copyright © 2002 John Wiley & Sons, Ltd. [source] Microfluidic chips for mass spectrometry-based proteomicsJOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 5 2009Jeonghoon Lee Abstract Microfluidic devices coupled to mass spectrometers have emerged as excellent tools for solving the complex analytical challenges associated with the field of proteomics. Current proteome identification procedures are accomplished through a series of steps that require many hours of labor-intensive work. Microfluidics can play an important role in proteomic sample preparation steps prior to mass spectral identification such as sample cleanup, digestion, and separations due to its ability to handle small sample quantities with the potential for high-throughput parallel analysis. To utilize microfluidic devices for proteomic analysis, an efficient interface between the microchip and the mass spectrometer is required. This tutorial provides an overview of the technologies and applications of microfluidic chips coupled to mass spectrometry for proteome analysis. Various approaches for combining microfluidic devices with electrospray ionization (ESI) and matrix-assisted laser desorption/ionization (MALDI) are summarized and applications of chip-based separations and digestion technologies to proteomic analysis are presented. Copyright © 2009 John Wiley & Sons, Ltd. [source] Recrystallization behaviour of the nickel-based alloy 80 A during hot formingJOURNAL OF MICROSCOPY, Issue 3 2007S. MITSCHE Summary The dynamic recrystallization as well as meta-dynamic and static recrystallization of the nickel-based alloy 80A was investigated by means of electron backscatter diffraction (EBSD). Specimens were hot compressed at a temperature of 1120°C and a strain rate of 0.1/s at varying strain and soak times to describe the recrystallization behaviour. Various approaches were tested in order to differentiate between recrystallized and deformed grains based on EBSD data. The grain orientation spread was clearly found to be the most reliable procedure. A high twinning of the recrystallized grains was observed, and as a consequence the measured grain size was strongly dependent on whether the coherent and incoherent twin boundaries were regarded as genuine boundaries or removed. [source] Recent advances in controlled/living radical polymerization in emulsion and dispersionJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 21 2008Jung Kwon Oh Abstract Effective ways to conduct controlled/living radical polymerization (CRP) in emulsion systems are necessary for commercial latex production without significant modification of current industrial facilities. Conducting CRP in emulsion media is more complicated and more challenging than its application in homogeneous bulk. These challenges come from the intrinsic kinetics of emulsion polymerization. They include mass transport, slow chain growth mechanism, and exit of short radicals from polymeric particles. This review describes the recent developments of CRP in heterogeneous dispersion, including miniemulsion, microemulsion, dispersion, and especially emulsion. Various approaches for conducting emulsion CRP are detailed, including controlled seeded emulsion polymerization, nanoprecipitation, use of short oligomers as macroinitiators for in situ block copolymerization, and RAFT-mediated self-assembly. In addition many remaining challenges of the current methods barring wide spread industrial application of emulsion CRP are also suggested. © Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 6983,7001, 2008 [source] Dioxin-like and non-dioxin like effects of polychlorinated biphenyls: Implications for risk assessmentLAKES & RESERVOIRS: RESEARCH AND MANAGEMENT, Issue 3 2002John P. Giesy Abstract Polychlorinated biphenyls (PCBs) are persistent, bioaccumulative and toxic contaminants in the environment. Individual PCB congeners exhibit different physicochemical properties and biological activities that result in different environmental distributions and toxicity profiles. The variable composition of PCB residues in environmental matrices and their different mechanisms of toxicity complicate the development of scientifically based regulations for risk assessment. Various approaches for the assessment of risks of PCBs have been critically examined. Recent developments in the toxic equivalency factor (TEF) approach for the assessment of toxic effects due to dioxin-like PCBs have been examined. The PCB exposure studies that describe non-dioxin-like toxic effects, particularly neurobehavioural effects and their effective doses in animals, were compiled. A comparative assessment of effective doses for dioxin-like and non-dioxin-like effects by PCBs has been made to evaluate the relative significance of non- ortho and ortho -substituted PCBs in risk assessment. Using mink as an example, relative merits and implications of using TEF and total PCB approaches for assessing the potential for toxic effects in wildlife were examined. There are several advantages and limitations associated with each method used for PCB risk assessment. Toxic effects due to coplanar PCBs occur at relatively smaller concentrations than those due to non-dioxin-like PCBs and, therefore, the TEF approach derives the risk assessment of PCBs in the environment. The need for the refinement of the TEF approach for more accurate assessment of risks is discussed. [source] Selection criteria for drug-like compoundsMEDICINAL RESEARCH REVIEWS, Issue 3 2003Ingo Muegge Abstract The fast identification of quality lead compounds in the pharmaceutical industry through a combination of high throughput synthesis and screening has become more challenging in recent years. Although the number of available compounds for high throughput screening (HTS) has dramatically increased, large-scale random combinatorial libraries have contributed proportionally less to identify novel leads for drug discovery projects. Therefore, the concept of ,drug-likeness' of compound selections has become a focus in recent years. In parallel, the low success rate of converting lead compounds into drugs often due to unfavorable pharmacokinetic parameters has sparked a renewed interest in understanding more clearly what makes a compound drug-like. Various approaches have been devised to address the drug-likeness of molecules employing retrospective analyses of known drug collections as well as attempting to capture ,chemical wisdom' in algorithms. For example, simple property counting schemes, machine learning methods, regression models, and clustering methods have been employed to distinguish between drugs and non-drugs. Here we review computational techniques to address the drug-likeness of compound selections and offer an outlook for the further development of the field. © 2003 Wiley Periodicals, Inc. Med Res Rev, 23, No. 3, 302-321, 2003 [source] Design of Multi-Component Reactions: From Libraries of Compounds to Libraries of ReactionsMOLECULAR INFORMATICS, Issue 5-6 2006Maxim Abstract Multi-Component Reactions (MCRs) constitute a methodology to shorter syntheses of natural products or complex molecules similar to natural. Due to the large number of accessible compounds and other advantages, this type of chemistry has become very popular in the community of combinatorial chemists. In the last 5 years combinatorial chemistry is has evolved from the synthesis of libraries based on one scaffold to the synthesis of structurally diverse compounds, better known as diversity-oriented synthesis. Following this trend, the design of MCRs is becoming a tool kit for chemists to explore chemistry space broadly with complex and diverse structures. Various approaches to the creation of novel MCRs including "union of MCRs", "substrate design", and "reaction operator" are discussed here. [source] Expertise Research Methodology: Identifying Differences and Factors Influencing High and Low PerformancePERFORMANCE IMPROVEMENT QUARTERLY, Issue 4 2001Michael A. Horst ABSTRACT Expertise research methodologies have focused upon the identification of differences and factors influencing high and low performance at the individual, process, and organizational level. The goal of this review is to use the results to facilitate performance improvement through the investigation of high and low performing entities. Various approaches are reported in the literature to investigate expertise and quantify factors relating to development of this expertise at the individual, group, and organizational level. This review of research literature focuses upon studies utilizing expertise methodologies outside of the laboratory for identification of differences and factors influencing high and low performance. Studies cited emphasize performance at the individual, process, or organizational level. Statistical methods and techniques for identifying high and low performance are identified. Results have implications for use in performance improvement initiatives in assessing differences or factors influencing performance as well as identification of interventions and outcome measures. [source] CD40-expressing plasmid induces anti-CD40 antibody and enhances immune responses to DNA vaccinationTHE JOURNAL OF GENE MEDICINE, Issue 1 2010Hanqian Xu Abstract Background Various approaches have been used to improve the efficacy of DNA vaccination, including the incorporation of molecular adjuvants. Because the CD40 ligand,CD40 interaction plays a major role in initiating immune responses, we sought to develop a molecular adjuvant targeting this interaction. Methods and Results We immunized mice with a foot-and-mouth disease virus DNA vaccine, pcD-VP1, together with a CD40-expressing plasmid, pcD-CD40. We found that pcD-CD40 induced anti-CD40 antibodies, which temporally correlated with the augmented production of anti-VP1 antibody. pcD-CD40 similarly augmented the humoral response of another DNA vaccine that targets hepatitis B virus, and passive transfer of anti-CD40 antisera also showed a similar effect. Furthermore, the pcD-CD40-elicited anti-CD40 antibodies were able to activate the CD40 signal pathway in antigen-presenting cells in vitro, which led to the maturation of dendritic cells (DCs) and DC-mediated T cell activation. Thus, pcD-CD40 augments DNA vaccination by inducing anti-CD40 antibodies, which in turn promotes T cell activation. Conclusions This is the first reported ,proadjuvant' that augments DNA vaccination indirectly by eliciting agonistic antibodies. Copyright © 2009 John Wiley & Sons, Ltd. [source] Querkrafttragfähigkeit von Fahrbahnplatten ohne QuerkraftbewehrungBETON- UND STAHLBETONBAU, Issue 10 2009Günter Rombach Prof. Dr.-Ing. Versuche; Berechnungs- und Bemessungsverfahren Abstract Es wird über Versuche zur Querkrafttragfähigkeit von Brückenfahrbahnplatten aus Stahlbeton berichtet. Diese zeigen, dass die bekannten Rechenansätze für Bauteile ohne Querkraftbewehrung nach DIN 1045-1 bzw. DIN-FB 102 für Fahrbahnplatten auf der sicheren Seite liegen, die tatsächliche Tragfähigkeit aber weit unterschätzt wird. Weitere Ansätze zur Berechnung der Querkrafttragfähigkeit von Stahlbetonbauteilen ohne Querkraftbewehrung werden erörtert. Während die Modelle bei der Auswertung einer Datenbank von Balkenversuchen eine gute Übereinstimmung aufweisen, zeigt der Vergleich mit den Modellversuchen, dass die meisten Rechenverfahren die Tragfähigkeit der Platten unterschätzen. Zur Berechnung der Querkrafttragfähigkeit von Platten ohne Querkraftbewehrung unter Punktlasten wird ein Modell vorgeschlagen, welches die Querkrafttragfähigkeit mit der Zugbeanspruchung der Biegezugzone im kritischen Bereich verknüpft. Shear Resistance of Bridge Decks without Transverse Reinforcement The design of concrete bridge deck slabs is of major concern since the introduction of the Eurocodes as the calculated shear capacity of slabs without stirrups and staggered reinforcement according to the new design standards is often considerably smaller compared to the former regulations i.e. DIN 1045:88. This raises the question whether the existing structures are still save. A series of 12 tests on 4 different specimens representing a bridge deck was performed to examine the real load bearing behaviour of a slab with and without shear reinforcement under a wheel (point) load. The evaluation of the test results revealed, that the current design formula with an assumed elastic shear force distribution leads to rather conservative values of shear capacity for bridge deck slabs. Various approaches for shear design are discussed and the accuracy is checked by means of a shear database and the test results. A new model to calculate the shear capacity is proposed which shows a better agreement with test data than the known approaches. [source] On web communities mining and recommendationCONCURRENCY AND COMPUTATION: PRACTICE & EXPERIENCE, Issue 5 2009Yanchun Zhang Abstract Because of the lack of a uniform schema for web documents and the sheer amount and dynamics of web data, both the effectiveness and the efficiency of information management and retrieval of web data are often unsatisfactory when using conventional data management and searching techniques. To address this issue, we have adopted web mining and web community analysis approaches. On the basis of the analysis of web document contents, hyperlinks analysis, user access logs and semantic analysis, we have developed various approaches or algorithms to construct and analyze web communities, and to make recommendations. This paper will introduce and discuss several approaches on web community mining and recommendation. Copyright © 2009 John Wiley & Sons, Ltd. [source] An Agency Theory Perspective on Student Performance EvaluationDECISION SCIENCES JOURNAL OF INNOVATIVE EDUCATION, Issue 1 2005Michael E. Smith ABSTRACT The emphasis in recent research on the responsibility of college and university business instructors to prepare students for future employment underscores a need to refine the evaluation of student performance. In this article, an agency theory framework is used to understand the trade-offs that may be involved in the selection of various approaches to student evaluation. Understanding these trade-offs may be particularly important as faculty members seek to balance competing obligations, such as research and service requirements, while ensuring instructional effectiveness. This article presents propositions for examining how various institutional, instructor, and student characteristics influence the selection and use of student performance evaluation techniques (i.e., exams, papers, and group assignments). In conclusion, we suggest that agency theory may serve as a foundation for understanding current evaluation practices and guiding instructors in their selection of appropriate evaluation mechanisms. [source] Effect of treatment delay upon pulp and periodontal healing of traumatic dental injuries , a review articleDENTAL TRAUMATOLOGY, Issue 3 2002J.O. Andreasen Abstract,,,Based on an analysis of the literature concerning parameters influencing the prognosis of traumatic dental injuries, few studies were found to have examined possible relationships between treatment delay and pulpal and periodontal ligament healing complications. It has been commonly accepted that all injuries should be treated on an emergency basis, for the comfort of the patient and also to reduce wound healing complications. For practical and especially economic reasons, various approaches can be selected to fulfill such a demand, such as acute treatment (i.e. within a few hours), subacute (i.e. within the first 24 h), and delayed (i.e. after the first 24 h). In this survey the consequences of treatment delay on pulpal and periodontal healing have been analyzed for the various dental trauma groups. Applying such a treatment approach to the various types of injuries, the following treatment guidelines can be recommended, based on our present rather limited knowledge of the effect of treatment delay upon wound healing. Crown and crown/root fractures: Subacute or delayed approach. Root fractures: Acute or subacute approach. Alveolar fractures: Acute approach (evidence however questionable). Concussion and subluxation: Subacute approach. Extrusion and lateral luxation: Acute or subacute approach (evidence however questionable). Intrusion: Subacute approach (evidence however questionable). Avulsion: If the tooth is not replanted at the time of injury, acute approach; otherwise subacute. Primary tooth injury: Subacute approach, unless the primary tooth is displaced into the follicle of the permanent tooth or occlusal problems are present; in the latter instances, an acute approach should be chosen. These treatment guidelines are based on very limited evidence from the literature and should be revised as soon as more evidence about the effect of treatment delay becomes available. [source] Collective Action and Property Rights for Poverty Reduction: A Review of Methods and ApproachesDEVELOPMENT POLICY REVIEW, Issue 3 2009Esther Mwangi This article provides a review of literature on the relationship between poverty and the institutions of collective action and property rights, as outlined in the conceptual framework of Di Gregorio et al. (2008). Using the elements of the framework as a guide, it offers an overview of how researchers and practitioners identify and evaluate these concepts. The article emphasises the multidimensionality of poverty and the necessity of applying various approaches and tools to conceptualising and measuring it. In addition to highlighting the crucial role that institutions play in poverty reduction, it shows power relations and the political context to be of fundamental importance in poverty-related studies. [source] A spatial model of bird abundance as adjusted for detection probabilityECOGRAPHY, Issue 2 2009P. Marcos Gorresen Modeling the spatial distribution of animals can be complicated by spatial and temporal effects (i.e. spatial autocorrelation and trends in abundance over time) and other factors such as imperfect detection probabilities and observation-related nuisance variables. Recent advances in modeling have demonstrated various approaches that handle most of these factors but which require a degree of sampling effort (e.g. replication) not available to many field studies. We present a two-step approach that addresses these challenges to spatially model species abundance. Habitat, spatial and temporal variables were handled with a Bayesian approach which facilitated modeling hierarchically structured data. Predicted abundance was subsequently adjusted to account for imperfect detection and the area effectively sampled for each species. We provide examples of our modeling approach for two endemic Hawaiian nectarivorous honeycreepers: ,i,iwi Vestiaria coccinea and ,apapane Himatione sanguinea. [source] Electrochemical Nitric Oxide Sensors for Biological Samples , Principle, Selected Examples and ApplicationsELECTROANALYSIS, Issue 1 2003Fethi Bedioui Abstract The discoveries made in the 1980s that NO could be synthesized by mammalian cells and could act as physiological messenger and cytotoxic agent had elevated the importance of its detection. The numerous properties of NO, that enable it to carry out its diverse functions, also present considerable problems when attempting its detection and quantification in biological systems. Indeed, its total free concentration in physiological conditions has been established to be in nanomolar range. Thus, detection of nitric oxide remains a challenge, pointing out the difficult dual requirements for specificity and sensitivity. Exception made for the electrochemical techniques, most of the approaches (namely UV-visible spectroscopy, fluorescence, electron paramagnetic resonance spectroscopy) use indirect methods for estimating endogenous NO, relying on measurements of secondary species such as nitrite and nitrate or NO-adducts. They also suffer from allowing only ex situ measurements. So, the only strategies that allow a direct and in vivo detection of NO are those based on the use of ultramicroelectrodes. The reality is that surface electrode modification is needed to make the ultramicroelectrode material selective for NO. Therefore, the design of modified electrode surfaces using organized layers is very attractive and provides the ideal strategy. This review addresses a global description of the various approaches that have involved chemically modified microelectrodes specially designed for the electrochemical detection of NO in biological media. Selected significant examples of applications in biological tissues are also reported in order to highlight the importance of this approach in having new insights into the modulatory role of NO in physiology and pathophysiology. [source] Classification of abused inhalantsADDICTION, Issue 6 2009Robert L. Balster ABSTRACT Many hundreds of household and industrial products can be volatilized readily and are subject to abuse. Inhalant abuse research has been hampered by a lack of consensus on whether or not there are subclassifications of abused inhalants based on chemical structure, form or intended use of the product or pharmacological properties. This paper discusses strengths and weaknesses of various approaches to classification of inhalants and suggests areas for future research in this area. It is concluded that classification of inhalants by form or product types is not useful for scientific purposes; rather, subclassification of inhalants should be based on a yet-to-be-determined combination of chemical and pharmacological similarity and shared patterns of abuse. One of the ways in which we can improve our understanding of inhalant abuse is to obtain more detailed information on individual products and chemicals, their patterns of use and the geographical distribution of their use. [source] Recent progress in enantiomeric separation by capillary electrochromatographyELECTROPHORESIS, Issue 22-23 2002Jingwu Kang Abstract Recent progress in enantiomeric separations by capillary electrochromatography (CEC) is reviewed. The development of simple and robust CEC column technologies plays an important role for popularization of CEC. During the last several years, various approaches for the preparation of enantioselective columns have been reported. Currently, the monolithic column technology (continuous beds) represents the most advanced approach for the preparation of CEC columns. The development of new chiral stationary phase used for CEC is another important issue in this field. Fundamental investigations on electrochromatographic behaviors of various CSPs are necessary in order to understand the separation mechanism and thus improve the separation performance. Some chiral stationary phases performed better under nonaqueous CEC conditions than reversed-phase conditions. Coupling CEC with mass spectrometry (MS) provides a powerful tool for enantiomeric separation. Finally, some applications of enantiomeric separation by CEC are summarized. [source] Development and evaluation of consensus-based sediment effect concentrations for polychlorinated biphenyls,ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 5 2000Donald D. MacDonald Abstract Sediment-quality guidelines (SQGs) have been published for polychlorinated biphenyls (PCBs) using both empirical and theoretical approaches. Empirically based guidelines have been developed using the screening-level concentration, effects range, effects level, and apparent effects threshold approaches. Theoretically based guidelines have been developed using the equilibrium-partitioning approach. Empirically-based guidelines were classified into three general categories, in accordance with their original narrative intents, and used to develop three consensus-based sediment effect concentrations (SECs) for total PCBs (tPCBs), including a threshold effect concentration, a midrange effect concentration, and an extreme effect concentration. Consensus-based SECs were derived because they estimate the central tendency of the published SQGs and, thus, reconcile the guidance values that have been derived using various approaches. Initially, consensus-based SECs for tPCBs were developed separately for freshwater sediments and for marine and estuarine sediments. Because the respective SECs were statistically similar, the underlying SQGs were subsequently merged and used to formulate more generally applicable SECs. The three consensus-based SECs were then evaluated for reliability using matching sediment chemistry and toxicity data from field studies, dose-response data from spiked-sediment toxicity tests, and SQGs derived from the equilibrium-partitioning approach. The results of this evaluation demonstrated that the consensus-based SECs can accurately predict both the presence and absence of toxicity in field-collected sediments. Importantly, the incidence of toxicity increases incrementally with increasing concentrations of tPCBs. Moreover, the consensus-based SECs are comparable to the chronic toxicity thresholds that have been estimated from dose-response data and equilibrium-partitioning models. Therefore, consensus-based SECs provide a unifying synthesis of existing SQGs, reflect causal rather than correlative effects, and accurately predict sediment toxicity in PCB-contaminated sediments. [source] Enhancement of learning behaviour by a potent nitric oxide-guanylate cyclase activator YC-1EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 6 2005Wei-Lin Chien Abstract Memory is one of the most fundamental mental processes, and various approaches have been used to understand the mechanisms underlying this process. Nitric oxide (NO), cGMP and protein kinase G (PKG) are involved in the modulation of synaptic plasticity in various brain regions. YC-1, which is a benzylindazole derivative, greatly potentiated the response of soluble guanylate cyclase to NO (up to several hundreds fold). We have previously shown that YC-1 markedly enhances long-term potentiation in hippocampal and amygdala slices via NO-cGMP-PKG-dependent pathway. We here further investigated whether YC-1 promotes learning behaviour in Morris water maze and avoidance tests. It was found that YC-1 shortened the escape latency in the task of water maze, increased and decreased the retention scores in passive and active avoidance task, respectively. Administration of YC-1 30 min after foot-shock stimulation did not significantly affect retention scores in response to passive avoidance test. Administration of scopolamine, a muscarinic antagonist, markedly impaired the memory acquisition. Pretreatment of YC-1 inhibited the scopolamine-induced learning deficit. The enhancement of learning behaviour by YC-1 was antagonized by intracerebroventricular injection of NOS inhibitor L-NAME and PKG inhibitors of KT5823 and Rp-8-Br-PET-cGMPS, indicating that NO-cGMP-PKG pathway is also involved in the learning enhancement action of YC-1. YC-1 is thus a good drug candidate for the improvement of learning and memory. [source] An Overview of the Anatomy of Crystal Plasticity ModelsADVANCED ENGINEERING MATERIALS, Issue 9 2009Georges Cailletaud Abstract Single crystals, polycrystals, and DS alloys can be modeled in the same framework by means of crystal plasticity. This paper wants to show the common features of the different approaches on the grain level, and the additional assumptions that are needed to derive polycrystal or DS models. Phenomenological rules are introduced for representing the hardening in the single crystal constitutive equations. Series of examples are given to illustrate the capabilities of the various approaches that are mainly related to the crystallographic character, and to the fact that the macroscopic yield locus is not predefined, but built from a collection of linear yield conditions. [source] Ancestors and variants: tales from the crypticEVOLUTION AND DEVELOPMENT, Issue 3 2000William E. Browne SUMMARY Those who work at the interface of development and evolution are united by the conviction that developmental comparisons can shed light on both the evolution of specific morphologies and the macroevolutionary process itself. In practice, however, the field comprises a diversity of approaches. As the field grows and practitioners attempt to digest a growing mountain of comparative data, the various approaches of "Evo Devo" have themselves evolved. A meeting organized by the authors and held at the University of Chicago in the Spring of 1999 illustrated some of these changes. This review will draw on its content to discuss recent developments in two areas: the reconstruction of common ancestors and the developmental basis of evolutionary change. [source] Anti-adhesion therapy of bacterial diseases: prospects and problemsFEMS IMMUNOLOGY & MEDICAL MICROBIOLOGY, Issue 3 2003Itzhak Ofek Abstract The alarming increase in drug-resistant bacteria makes a search for novel means of fighting bacterial infections imperative. An attractive approach is the use of agents that interfere with the ability of the bacteria to adhere to tissues of the host, since such adhesion is one of the initial stages of the infectious process. The validity of this approach has been unequivocally demonstrated in experiments performed in a wide variety of animals, from mice to monkeys, and recently also in humans. Here we review various approaches to anti-adhesion therapy, including the use of receptor and adhesin analogs, dietary constituents, sublethal concentrations of antibiotics and adhesin-based vaccines. Because anti-adhesive agents are not bactericidal, the propagation and spread of resistant strains is much less likely to occur than as a result of exposure to bactericidal agents, such as antibiotics. Anti-adhesive drugs, once developed, may, therefore, serve as a new means to fight infectious diseases. [source] A large carbon pool and small sink in boreal Holocene lake sedimentsGLOBAL CHANGE BIOLOGY, Issue 10 2004Pirkko Kortelainen Abstract Model-based estimates suggest that lake sediments may be a significant, long-term sink for organic carbon (C) at regional to global scales. These models have used various approaches to predict sediment storage at broad scales from very limited data sets. Here, we report a large-scale direct assessment of the standing stock and sedimentation rate of C for a representative set of lakes in Finland. The 122 lakes were selected from the statistically selected Nordic Lake Survey database, they cover the entire country and the water quality represents the average lake water quality in Finland. Unlike all prior estimates, these data use sediment cores that comprise the entire sediment record. The data show that within Finland, aquatic ecosystems contain the second largest areal C stocks (19 kg C m,2) after peatlands (72 kg C m,2), and exceed by significant amounts stocks in the forest soil (uppermost 75cm; 7.2 kg C m,2) and woody biomass (3.4 kg C m,2). Kauppi et al. (1997). The Finnish estimate extrapolated over the boreal region gives a total C pool in lakes 19,27 Pg C, significantly lower than the previous model-based estimates. [source] Porcine factor VIII in the treatment of high-titre inhibitor patientsHAEMOPHILIA, Issue 2002M.B. Garvey Development of an inhibitor against factor VIII (FVIII) is an important complication of haemophilia. It occurs in approximately 25,30% of patients with haemophilia A [1]. FVIII inhibitors may also occur as autoantibodies. The latter occur in nonhaemophiliacs and, although rare (occurring in approximately one per million of the population), are frequently associated with life-threatening bleeding. Inhibitors are considered low level if they are < 5 Bethesda Units (BU) or high level if they are > 10 BU. The former usually remain low and rarely give anamnestic response, the latter do so frequently. Despite various approaches to their management, the presence of inhibitors remains a major cause of morbidity and mortality. The effectiveness of porcine FVIII (pFVIII) in treating patients with both auto- and alloantibodies to FVIII has been well demonstrated when adequate circulating levels of FVIII are obtained [2,10]. However, pFVIII therapy may give rise to antibodies to the pFVIII and the utility of this treatment in the presence of high levels of porcine antibody is less well recognized and understood. Nonetheless, pFVIII under these circumstances may be useful in a select group of patients where management is difficult. [source] What Do Patients With Migraine Want From Acute Migraine Treatment?HEADACHE, Issue 2002Richard B. Lipton MD Migraine is a common chronic condition with an ever-expanding therapeutic armamentarium. As therapeutic options multiply, it is increasingly important to understand patients' attitudes and preferences regarding various treatment characteristics. Several strategies have evolved to establish treatment priorities in migraine and rationalize and prioritize end points and outcomes to meet the needs of patients. A survey of a population-based sample of migraineurs indicated that an overwhelming majority of patients consider complete relief of head pain, no recurrence, and rapid onset of action as important or very important attributes of acute migraine therapy. An analysis of the relationship between clinical end points and satisfaction found that more than 90% of patients who were pain-free at 2 hours were at least somewhat satisfied with treatment, but satisfaction was dependent on relatively rapid relief. Using a "willingness-to-pay" approach, results indicated that while patients will pay more for migraine treatment that produces rapid, consistent relief without adverse effects or recurrence, speed of complete relief is the most valued attribute. By assessing physician preferences and practices, degree of pain relief and rapid onset were identified as the most important attributes of acute therapy. Based on results from preference studies of triptans, 50% of patients cited more rapid pain relief as the most important determinant of treatment preference. Based on these various approaches, the consensus view is that both clinicians and patients desire a broad range of positive migraine treatment attributes, but rapid onset of complete pain relief is a particularly important priority. [source] | ||||||||||||||||||||||||||||||||||