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Selected AbstractsTransformative Teaching: Restoring the teacher, under erasureEDUCATIONAL PHILOSOPHY AND THEORY, Issue 2 2009Jenny Steinnes Abstract In the large and complex landscape of pedagogy, the focus seems to have turned away from the concept of teaching and towards a stronger emphasis on learning, probably supported by neo-liberal ideology. The teacher is presented more as part of the force of production than as an autonomous performer of a mandate given to him/her by society. He/she is supposed to supply knowledge that is considered useful to a society geared to production and consumption. During the past few decades, enlightenment as a legitimising concept for education has been challenged from different angles, both by a self-critique from within and from external forces. One angle of approach is the questioning of the relationship between the state and education, by way of a critique of modernity. Another approach comes from a critique of knowledge, which has lost most of its universal implications and is left with more pragmatic and utilitarian considerations. Into this landscape of lost legitimisation, I will make an attempt to visualise an impossible/possible position for teaching, featuring ancient, contemporary and phantom-like figures. I am suggesting the concept of transformation as an alternative to development or improvement, which I find to be concepts with a close link to modernity and its linearity. By a careful and conscious use of the word transformation, taking Derrida's intensified focus of language into account, a possible active position might be intimated in spite of the fundamental critique, which has been directed at pedagogy and its imperialistic implications from different angles. [source] Chemical modification of polyethersulfone nanofiltration membranes: A reviewJOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2009B. Van der Bruggen Abstract Polysulfone (PS) and poly(ether)sulfone (PES) are often used for synthesis of nanofiltration membranes, due to their chemical, thermal, and mechanical stability. The disadvantage for applying PS/PES is their high hydrophobicity, which increases membrane fouling. To optimize the performance of PS/PES nanofiltration membranes, membranes can be modified. An increase in membrane hydrophilicity is a good method to improve membrane performance. This article reviews chemical (and physicochemical) modification methods applied to increase the hydrophilicity of PS/PES nanofiltration membranes. Modification of poly(ether)sulfone membranes in view of increasing hydrophilicity can be carried out in several ways. Physical or chemical membrane modification processes after formation of the membrane create more hydrophilic surfaces. Such modification processes are (1) graft polymerization that chemically attaches hydrophilic monomers to the membrane surface; (2) plasma treatment, that introduces different functional groups to the membrane surface; and (3) physical preadsorption of hydrophilic components to the membrane surface. Surfactant modification, self-assembly of hydrophilic nanoparticles and membrane nitrification are also such membrane modification processes. Another approach is based on modification of polymers before membrane formation. This bulk modification implies the modification of membrane materials before membrane synthesis of the incorporation of hydrophilic additives in the membrane matrix during membrane synthesis. Sulfonation, carboxylation, and nitration are such techniques. To conclude, polymer blending also results in membranes with improved surface characteristics. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 [source] Mechanisms of cytochrome P450 substrate oxidation: MiniReviewJOURNAL OF BIOCHEMICAL AND MOLECULAR TOXICOLOGY, Issue 4 2007F. Peter Guengerich Abstract Cytochrome P450 (P450) enzymes catalyze a variety of oxidation and some reduction reactions, collectively involving thousands of substrates. A general chemical mechanism can be used to rationalize most of the oxidations and involves a perfenyl intermediate (FeO3+) and odd-electron chemistry, i.e. abstraction of a hydrogen atom or electron followed by oxygen rebound and sometimes rearrangement. This general mechanism can explain carbon hydroxylation, heteroatom oxygenation and dealkylation, epoxidation, desaturation, heme destruction, and other reactions. Another approach to understanding catalysis involves analysis of the more general catalytic cycle, including substrate specificity, because complex patterns of cooperativity are observed with several P450s. Some of the complexity is due to slow conformational changes in the proteins that occur on the same timescale as other steps. © 2007 Wiley Periodicals, Inc. J Biochem Mol Toxicol 21:163,168, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/jbt.20174 [source] Increased expression of glial cell line-derived neurotrophic factor protects against oxidative damage-induced retinal degenerationJOURNAL OF NEUROCHEMISTRY, Issue 3 2007Aling Dong Abstract Oxidative damage contributes to retinal cell death in patients with age-related macular degeneration or retinitis pigmentosa. One approach to treatment is to identify and eliminate the sources of oxidative damage. Another approach is to identify treatments that protect cells from multiple sources of oxidative damage. In this study, we investigated the effect of increased expression of glial cell line-derived neurotrophic factor (GDNF) in three models of oxidative damage-induced retinal degeneration. Double transgenic mice with doxycycline-inducible expression of GDNF in the retina were exposed to paraquat, FeSO4, or hyperoxia, all sources of oxidative damage and retinal cell death. Compared to controls, mice with increased expression of GDNF in the retina showed significant preservation of retinal function measured by electroretinograms, reduced thinning of retinal cell layers, and fewer TUNEL-positive cells indicating less retinal cell death. Mice over-expressing GDNF also showed less staining for acrolein, nitrotyrosine, and 8-hydroxydeoxyguanosine, indicating less oxidative damage to lipids, proteins, and DNA. This suggests that GDNF did not act solely to allow cells to tolerate higher levels of oxidative damage before initiation of apoptosis, but also reduced damage from oxidative stress to critical macromolecules. These data suggest that gene transfer of Gdnf should be considered as a component of therapy for retinal degenerations in which oxidative damage plays a role. [source] Recent advances in non-invasive prenatal DNA diagnosis through analysis of maternal bloodJOURNAL OF OBSTETRICS AND GYNAECOLOGY RESEARCH (ELECTRONIC), Issue 6 2007Akihiko Sekizawa Abstract Prenatal diagnosis of aneuploidy and single-gene disorders is usually performed by collecting fetal samples through amniocentesis or chorionic villus sampling. However, these invasive procedures are associated with some degree of risk to the fetus and/or mother. Therefore, in recent years, considerable effort has been made to develop non-invasive prenatal diagnostic procedures. One potential non-invasive approach involves analysis of cell-free fetal DNA in maternal plasma or serum. Another approach utilizes fetal cells within the maternal circulation as a source of fetal DNA. At the present time, fetal gender and fetal RhD blood type within RhD-negative pregnant women can be reliably determined through analysis of maternal plasma. Furthermore, genetic alterations can be diagnosed in the maternal plasma when the mother does not have the alterations. However, the diagnosis of maternally inherited genetic disease and aneuploidy is limited using this approach. Non-invasive prenatal diagnosis through examination of intact fetal cells circulating within maternal blood can be used to diagnose a full range of genetic disorders. Since only a limited number of fetal cells circulate within maternal blood, procedures to enrich the cells and enable single cell analysis with high sensitivity are required. Recently, separation methods, including a lectin-based method and autoimage analyzing, have been developed, which have improved the sensitivity of genetic analysis. This progress has supported the possibility of non-invasive prenatal diagnosis of genetic disorders. In the present article, we discuss recent advances in the field of non-invasive prenatal diagnosis. [source] Inhibition of proprotein convertases: Approaches to block squamous carcinoma development and progressionMOLECULAR CARCINOGENESIS, Issue 8 2007Ricardo López de Cicco Abstract Most proprotein convertase (PC) inhibitors are compounds that act as competitive inhibitors. All of them contain the general cleavage motif RXK/RR that binds to the PC's active site impairing further interactions with their physiological substrates. The first inhibitors synthesized were the acyl-peptidyl-chloromethyl ketones that bind to the PC's active site through its peptidyl group and are able to transverse the plasma membrane due to the acyl moiety. For instance, one of the members of this family that exhibits reduced toxicity and has been widely used as an effective general PCs inhbitor is the derivative decanoyl-RVKR-chloromethylketone (CMK). Another approach to PC inhibition is based on proteins that contain either a natural or a bioengineered PC cleavage consensus site. In this context, the bioengineered serpin, alpha-1-antitrypsin Portland (alpha 1-PDX or PDX), proved to be a potent inhibitor of furin, the most studied of the cancer-related PCs. Both PDX and CMK were able to inhibit invasiveness of squamous cell carcinoma cell lines by blocking activation of cancer-associated PC substrates such as MT-MMPs, IGF-1R, and VEGF-C. A similar effect was produced by inhibiting PC-mediated processing using furin prosegment. PDX and CMK have also been assayed in vivo using skin carcinogenesis models. Newer promising small molecules and RNA interference approaches are also being developed to inhibit PCs. © 2007 Wiley-Liss, Inc. [source] Data analysis in plant physiology: are we missing the reality?PLANT CELL & ENVIRONMENT, Issue 9 2001G. N. Amzallag Abstract In plant physiology, data analysis is based on the comparison of mean values. In this perspective, variability around the mean value has no significance per se, but only for estimating statistical significance of the difference between two mean values. Another approach to variability is proposed here, derived from the difference between redundant and deterministic patterns of regulation in their capacity to buffer noise. From this point of view, analysis of variability enables the investigation of the level of redundancy of a regulation pattern, and even allows us to study its modifications. As an example, this method is used to investigate the effect of brassinosteroids (BSs) during vegetative growth in Sorghum bicolor. It is shown that, at physiological concentrations, BSs modulate the network of regulation without affecting the mean value. Thus, it is concluded that the physiological effect of BSs cannot be revealed by comparison of mean values. This example illustrates how a part of the reality (in this case, the most relevant one) is hidden by the classical methods of comparison between mean values. The proposed tools of analysis open new perspectives in understanding plant development and the non-linear processes involved in its regulation. They also ask for a redefinition of fundamental concepts in physiology, such as growth regulator, optimality, stress and adaptation. [source] Becoming Deliberative Citizens: The Moral Learning Process of the Citizen JurorPOLITICAL STUDIES, Issue 4 2010Shane Doheny This article presents an analysis of qualitative interviews carried out with citizen jurors at least three years after they participated in a jury. Theoretical work on deliberation tends to emphasise the transformative effect of deliberation. Much empirical work has focused on this transformation conceived as the re-prioritisation of preferences, and examines whether and how jurors change their personal and political commitments as a result of their participation on a jury. Another approach to transformation is more discursive, and hypothesises that the concepts and perspectives that jurors use to evaluate norms may also be transformed. This article presents qualitative data that illuminate this latter hypothesis. Specifically, the article analyses the stories ex-jurors told of their participation in citizen juries, in order to chart changes in the concepts and perspectives that jurors use to evaluate norms. By analysing these stories we identify four juror roles , envoy, regulator, advocate and deliberator , and we elaborate these using Habermas' learning theory. Overall our argument is that the citizen juror is given the opportunity to undertake a learning process, and through this process they are furnished with new concepts and perspectives with which to evaluate norms. Moreover, Habermas theorises that this learning process cumulates with the formation of a deliberative citizen who thinks using the characteristics described in discourse ethics. Here we identify discourses that support this claim. [source] Mixed matrix membrane materials with glassy polymers.POLYMER ENGINEERING & SCIENCE, Issue 7 2002Part Analysis presented in Part 1 of this paper indicated the importance of optimization of the transport properties of the interfacial region to achieve ideal mixed matrix materials. This insight is used in this paper to guide mixed matrix material formation with more conventional gas separation polymers. Conventional gas separation materials are rigid, and, as seen earlier, lead to the formation of an undesirable interphase under conventional casting techniques. We show in this study that if flexibility can be maintained during membrane formation with a polymer that interacts favorably with the sieve, successful mixed matrix materials result, even with rigid polymeric materials. Flexibility during membrane formation can be achieved by formation of films at temperatures close to the glass transition temperature of the polymer. Moreover, combination of chemical coupling and flexibility during membrane formation produces even more significant improvements in membrane performance. This approach leads to the formation of mixed matrix material with transport properties exceeding the upper bound currently achieved by conventional membrane materials. Another approach to form successful mixed matrix materials involves tailoring the interface by use of integral chemical linkages that are intrinsically part of the chain backbone. Such linkages appear to tighten the interface sufficiently to prevent "nonselective leakage" along the interface. This approach is demonstrated by directly bonding a reactive polymer onto the sieve surface under proper processing conditions. [source] Flow Distribution During Cardiopulmonary Bypass in Dependency on the Outflow Cannula PositioningARTIFICIAL ORGANS, Issue 11 2009Tim A.S. Kaufmann Abstract Oxygen deficiency in the right brain is a common problem during cardiopulmonary bypass (CPB). This is linked to an insufficient perfusion of the carotid and vertebral artery. The flow to these vessels is strongly influenced by the outflow cannula position, which is traditionally located in the ascending aorta. Another approach however is to return blood via the right subclavian artery. A computational fluid dynamics (CFD) study was performed for both methods and validated by particle image velocimetry (PIV). A 3-dimensional computer aided design model of the cardiovascular (CV) system was generated from realtime computed tomography and magnetic resonance imaging data. Mesh generation (CFD) and rapid prototyping (PIV) were used for the further model creation. The simulations were performed assuming usual CPB conditions, and the same boundary conditions were applied for the PIV validation. The flow distribution was analyzed for 55 cannula positions inside the aorta and in relation to the distance between the cannula tip and the vertebral artery branch for subclavian cannulation. The study reveals that the Venturi effect due to the cannula jet appears to be the main reason for the loss in cerebral perfusion seen clinically. It provides a PIV-validated CFD method of analyzing the flow distribution in the CV system and can be transferred to other applications. [source] Large Bore Catheters with Surface Treatments versus Untreated Catheters for Vascular Access in HemodialysisARTIFICIAL ORGANS, Issue 7 2004Rolf Bambauer Abstract:, Infection, thrombosis, and stenosis are among the most frequent complications associated with blood-contacting catheters. Complications resulting from infection remain a major problem for hemodialysis catheters, with significant numbers of catheters being removed due to catheter-related sepsis. Numerous strategies have been employed to reduce the occurrence of infection and im-prove long-term outcomes, with varying degrees of success. The most important is the careful and sterile handling by the attending staff of the catheters during hemodialysis treatments to minimize or stop a microbial colonization of the skin and the catheter. Another approach is coating the external surface of the catheters with substances which are antibacterial like silver and/or substances with low thrombogenicity like silicone. This investigation reviews results of animal and clinical experiments conducted to assess the efficacy and biocompatibility of silver and silicone coated dialysis catheters. It is concluded that silver coatings can reduce bacterial colonization and occurrence of infection associated with these devices. The catheters employing ion implantation of silicone rubber showed low thrombogenicity. Results of the studies indicate that ion beam based processes can be used to improve thrombus and infection resistance of blood contacting catheters. A new development is the microdomain structured surface (PUR-SMA coated catheters). Preliminary results with these catheters are very encouraging. [source] Competing Risks and Time-Dependent CovariatesBIOMETRICAL JOURNAL, Issue 1 2010Giuliana Cortese Abstract Time-dependent covariates are frequently encountered in regression analysis for event history data and competing risks. They are often essential predictors, which cannot be substituted by time-fixed covariates. This study briefly recalls the different types of time-dependent covariates, as classified by Kalbfleisch and Prentice [The Statistical Analysis of Failure Time Data, Wiley, New York, 2002] with the intent of clarifying their role and emphasizing the limitations in standard survival models and in the competing risks setting. If random (internal) time-dependent covariates are to be included in the modeling process, then it is still possible to estimate cause-specific hazards but prediction of the cumulative incidences and survival probabilities based on these is no longer feasible. This article aims at providing some possible strategies for dealing with these prediction problems. In a multi-state framework, a first approach uses internal covariates to define additional (intermediate) transient states in the competing risks model. Another approach is to apply the landmark analysis as described by van Houwelingen [Scandinavian Journal of Statistics 2007, 34, 70,85] in order to study cumulative incidences at different subintervals of the entire study period. The final strategy is to extend the competing risks model by considering all the possible combinations between internal covariate levels and cause-specific events as final states. In all of those proposals, it is possible to estimate the changes/differences of the cumulative risks associated with simple internal covariates. An illustrative example based on bone marrow transplant data is presented in order to compare the different methods. [source] 4351: Using the OHTS-EGPS risk calculator with OctopusTM visual field testingACTA OPHTHALMOLOGICA, Issue 2010AM STEVENS Purpose Assessing risk in ocular hypertensive (OHT)patients is not only of clinical importance for the patients with regard to their possible glaucomatous field damage but has major repercussions on their quality of life when making decisions about the use of eye drops for longer periods. Clinicians are not that good in estimating the risk hence the need for instruments to help them make a more evidence-based decision. The EGPS group states that a methodological difference " of using in a quarter of the patients another type of perimeter could explain the Hasard Ratio for the Pattern Standard Deviation (PSD) of 1.66 in EGPS and 1.27 in OHTS . Hence our interest to recalculate a conversion of the Octopus G1 program ( mostly used for glaucoma ) to the Humphrey 30-2 in a Group of ocular hypertensives conform the inclusions of the OHTS thus providing a way to use the calculator more accurately. Methods 50 OHT patients recruited using the OHTS criteria were tested both with the Humphrey 30-2 program and the Octopus G1 program. The Humphrey PSD values were plotted against the square root of the Loss of Variance (sLV) and a conversion formula was calculated Results Our data generated the following conversion formula: Y = 0.4X + 1.1 Conclusion Our conversion permits a proper use of the risk calculator in OHT patients. There has been an attempt to convert the values from Humphrey 30-2 to Octopus 32 by Monhart based on the results of a study by Langerhorst. Another approach could be based on the algorithm described by Zeyen using HFA 24-2 and G1 Octopus but proves difficult to use in daily practice. EGPS simply used "converted" indices by taking the square root of LV for PSD. Our formula is based on the same population as OHTS but yields different results [source] Coping With Missing Attribute Values Based on Closest Fit in Preterm Birth Data: A Rough Set ApproachCOMPUTATIONAL INTELLIGENCE, Issue 3 2001Jerzy W. Grzymala-Busse Data mining is frequently applied to data sets with missing attribute values. A new approach to missing attribute values, called closest fit, is introduced in this paper. In this approach, for a given case (example) with a missing attribute value we search for another case that is as similar as possible to the given case. Cases can be considered as vectors of attribute values. The search is for the case that has as many as possible identical attribute values for symbolic attributes, or as the smallest possible value differences for numerical attributes. There are two possible ways to conduct a search: within the same class (concept) as the case with the missing attribute values, or for the entire set of all cases. For comparison, we also experimented with another approach to missing attribute values, where the missing values are replaced by the most common value of the attribute for symbolic attributes or by the average value for numerical attributes. All algorithms were implemented in the system OOMIS. Our experiments were performed on the preterm birth data sets provided by the Duke University Medical Center. [source] Specific thermal ablation of tumor cells using single-walled carbon nanotubes targeted by covalently-coupled monoclonal antibodiesINTERNATIONAL JOURNAL OF CANCER, Issue 12 2009Radu Marches Abstract CD22 is broadly expressed on human B cell lymphomas. Monoclonal anti-CD22 antibodies alone, or coupled to toxins, have been used to selectively target these tumors both in SCID mice with xenografted human lymphoma cell lines and in patients with B cell lymphomas. Single-walled carbon nanotubes (CNTs) attached to antibodies or peptides represent another approach to targeting cancer cells. CNTs convert absorbed near-infrared (NIR) light to heat, which can thermally ablate cells that have bound the CNTs. We have previously demonstrated that monoclonal antibodies (MAbs) noncovalently coupled to CNTs can specifically target and kill cells in vitro. Here, we describe the preparation of conjugates in which the MAbs are covalently conjugated to the CNTs. The specificity of both the binding and NIR-mediated killing of the tumor cells by the MAb-CNTs is demonstrated by using CD22+CD25, Daudi cells, CD22,CD25+ phytohemagglutinin-activated normal human peripheral blood mononuclear cells, and CNTs covalently modified with either anti-CD22 or anti-CD25. We further demonstrate that the stability and specificity of the MAb-CNT conjugates are preserved following incubation in either sodium dodecyl sulfate or mouse serum, indicating that they should be stable for in vivo use. © 2009 UICC [source] Poly(L-lysine) as a model drug macromolecule with which to investigate secondary structure and membrane transport, part I: physicochemical and stability studiesJOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 3 2002Montakarn Chittchang Low oral bioavailability of therapeutic peptides and proteins generally results from their poor permeability through biological membranes and enzymatic degradation in the gastrointestinal tract. Since different secondary structures exhibit different physicochemical properties such as hydrophobicity, size and shape, changing the secondary structure of a therapeutic polypeptide may be another approach to increasing its membrane permeation. Poly(L-lysine) was used as a model polypeptide. The objectives of this study were to induce secondary structural changes in poly(L-lysine) and to determine the time course over which a given conformer was retained. In addition, the hydrophobicity of each secondary structure of poly(L-lysine) was assessed. The circular dichroism (CD) studies demonstrated that the conditions employed could successfully induce the desired secondary structural changes in poly(L-lysine). The ,-helix conformer appeared to be more stable at 25° C whereas the ,-sheet conformer could be preserved at 37° C. On the other hand, the random coil conformer was retained at both temperatures. Significant losses of the ,-helix and the ,-sheet conformers were observed when the pH was reduced. The change in ionic strength did not affect any of the conformers. The octanol/buffer partitioning studies indicated that the ,-helix and the ,-sheet conformers exhibited significantly different (P< 0.05) hydrophobicities. In conclusion, variation of pH and temperature conditions can be used to induce secondary structural changes in poly(L-lysine). These changes are reversible when the stimuli are removed. The ,-helix and the ,-sheet conformers of poly(L-lysine) are more lipophilic than the native random coil conformer. Thus, poly(L-lysine) may represent an ideal model polypeptide with which to further investigate the effects of secondary structure on membrane diffusion or permeation. [source] Enhancing Controller Performance via Dynamic Data ReconciliationTHE CANADIAN JOURNAL OF CHEMICAL ENGINEERING, Issue 3 2005Shuanghua Bai Abstract Measured values of process variables are subject to measurement noise. The presence of measurement noise can result in detuned controllers in order to prevent excessive adjustments of manipulated variables. Digital filters, such as exponentially weighted moving average (EWMA) and moving average (MA) filters, are commonly used to attenuate measurement noise before controllers. In this article, we present another approach, a dynamic data reconciliation (DDR) filter. This filter employs discrete dynamic models that can be phenomenological or empirical, as constraints in reconciling noisy measurements. Simulation results for a storage tank and a distillation column under PI control demonstrate that the DDR filter can significantly reduce propagation of measurement noise inside control loops. It has better performance than the EWMA and MA filters, so that the overall performance of the control system is enhanced. Les valeurs mesurées des variables de procédé sont affectées par les bruits de mesure. La présence de bruit de mesure force de régler à la baisse les régulateurs afin de prévenir des mouvements excessifs des variables manipulées. Des filtres numériques, tels que les filtres à moyenne mobile pondérée exponentiellement (EWMA) et les filtres à moyenne mobile (MA), sont communément utilisés pour atténuer le bruit de mesure avant les régulateurs. On présente dans cet article une autre approche, soit un filtre dynamique de réconciliation de données (DDR). Ce filtre emploie des modèles dynamiques discrets qui peuvent être phénoménologiques ou empiriques comme contraintes pour réconcilier les mesures bruitées. Les résultats de simulation pour un réservoir de stockage et une colonne à distiller utilisant un régulateur PI montrent que le filtre DDR peut réduire de manière significative la propagation du bruit de mesure dans les boucles de régulation. Sa performance est meilleure que celles des filtres EWMA ou MA, et par conséquent la performance globale du système de commande s'en trouve accrue. [source] Joint hypothesis specification for unit root tests with a structural break,THE ECONOMETRICS JOURNAL, Issue 2 2006Josep Lluís Carrion-i-Silvestre Summary, Several tests based on a t -ratio have been proposed in the literature to decide the order of integration of a time series allowing for a structural break. However, another approach based on testing a joint hypothesis of unit root and the irrelevance of some nuisance parameters is also feasible. This paper proposes new unit root tests consistent with the presence of a structural break applying this second perspective. Our approach deals both with the case where the break is not allowed under the null hypothesis, and where it is allowed. Simulations investigate the performance of this proposal compared to the existing tests and show important gains in terms of power. [source] Laminin acts via focal adhesion kinase/phosphatidylinositol-3, kinase/protein kinase B to down-regulate ,1 -adrenergic receptor signalling in cat atrial myocytesTHE JOURNAL OF PHYSIOLOGY, Issue 3 2009Y. G. Wang We previously reported that short-term (2 h) plating of cat atrial myocytes on the extracellular matrix protein, laminin (LMN) decreases adenylate cyclase activity and ,1 -adrenergic receptor (,1 -AR) stimulation of L-type Ca2+ current (ICa,L). The present study sought to determine whether LMN-mediated down-regulation of ,1 signalling is due to down-regulation of adenylate cyclase and to gain insight into the signalling mechanisms responsible. ,1 -AR stimulation was achieved by 0.01 ,m isoproterenol (isoprenaline) plus 0.1 ,m ICI 118551, a selective ,2 -AR antagonist. Atrial myocytes were plated for at least 2 h on uncoated cover-slips (,LMN) or cover-slips coated with LMN (+LMN). As previously reported, ,1 -AR stimulation of ICa,L was significantly smaller in +LMN compared to ,LMN atrial myocytes. In ,LMN myocytes, 10 ,m LY294002 (LY), a specific inhibitor of PI-(3)K, had no effect on ,1 -AR stimulation of ICa,L. In +LMN myocytes, however, LY significantly increased ,1 -AR stimulation of ICa,L. Western blots revealed that compared with ,LMN myocytes, +LMN myocytes showed a significant increase in Akt phosphorylation at Ser-473, which was prevented by LY. In another approach, +LMN myocytes were infected (multiplicity of infection (MOI), 100; 24 h) with replication-defective adenoviruses (Adv) expressing dominant-negative inhibitors of focal adhesion kinase (FAK) (Adv-FRNK or Adv-Y397F-FAK) or Akt (Adv-dnAkt). Compared with control cells infected with Adv-,-galactosidase, cells infected with Adv-FRNK, Adv-Y397F-FAK or Adv-dnAkt each exhibited a significantly greater ,1 -AR stimulation of ICa,L. In ,LMN myocytes LY had no effect on forskolin (FSK)-stimulated ICa,L. However, in +LMN myocytes LY significantly increased FSK-stimulated ICa,L. Similar results were obtained in +LMN atrial myocytes infected with Adv-FRNK. We conclude that LMN binding to ,1 -integrin receptors acts via FAK/PI-(3)K/Akt to inhibit adenylate cyclase activity and thereby down-regulates ,1 -AR-mediated stimulation of ICa,L. These findings provide new insight into the cellular mechanisms by which the extracellular matrix can modulate atrial ,-AR signalling. [source] Phenotyping approaches for physiological breeding and gene discovery in wheatANNALS OF APPLIED BIOLOGY, Issue 3 2009M. Reynolds Abstract Conceptual models of drought-adaptive traits have been used in breeding to accumulate complementary physiological traits (PT) in selected progeny, resulting in distribution of advanced lines to rain-fed environments worldwide by the International Maize and Wheat Improvement Center (CIMMYT). Key steps in PT breeding at CIMMYT include characterisation of crossing block lines for stress adaptive mechanisms, strategic crossing among parents that encompass as many target traits as possible and early generation selection (EGS) of bulks for canopy temperature (CT). The approach has been successful using both elite × elite crosses as well as three way crosses involving stress adapted landraces. Other EGS techniques that are amenable to high throughput include measurement of spectral reflectance indices and stomatal aperture-related traits. Their genetic- and cost-effectiveness are supported by realisation of genetic yield gains in response to trait selection, and by economic analysis, respectively. Continual reselection within restricted gene pools is likely to lead to diminishing returns, however, exotic parents can be used to introduce new allelic diversity. Examples include landraces from the primary gene pool, and products of inter-specific hybridisation with the secondary gene pool consisting of closely related wheat genomes. Both approaches have been successful in introducing stress-adaptive traits. The main problem with knowing which genetic resource to use in wide-crossing is the uncertainty with which phenotypic expression can be extrapolated from one genome/genepool to another because of their unimproved or undomesticated genetic backgrounds. Nonetheless, their PT expression can be measured and used as a basis for investing in crossing or wide crossing. Discovering the genetic basis of PT is highly complex because putative QTLs may interact with environment and genetic background, including genes of major effect. Detection of QTLs was improved in mapping populations where flowering time was controlled, while new mapping populations have been designed by screening potential parents that do not contrast in the Rht, Ppd and Vrn alleles. Association genetics mapping is another approach that can be employed for gene discovery using exclusively agronomically improved material, thereby minimising the probability of identifying yield QTLs whose alleles have been already improved by conventional breeding. [source] Recovery and separation of cell lysate proteins using hydrogels guided by aqueous two-phase extraction principlesBIOTECHNOLOGY & BIOENGINEERING, Issue 2 2002Christopher S. Putka Abstract The addition of poly(ethylene glycol) and salts to clarified cell lysates of Thiosphaera pantotropha increases sorption of microbial proteins into dextran hydrogels, consistent with the thermodynamics of aqueous two-phase extraction. Addition of 12 wt% PEG-10,000 to the lysate increased total sorption of protein by the dextran gel from 5.2 mg/g dextran to 37 mg/g; addition of either 0.1 M potassium iodide or tetrabutylammonium fluoride along with PEG to the lysate increased protein sorption to more than 63 mg/g, a 12-fold increase. SDS-PAGE demonstrated that the type of salt added controls which proteins are absorbed by the gel. Previously demonstrated only with model solutions, these results suggest another approach to recovery and separation strategies for proteins produced by fermentation. © 2002 Wiley Periodicals, Inc. Biotechnol Bioeng 80: 139,143, 2002. [source] | ||||||||||||||||||||||