489 resultados para Converts
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Introduction Nucleoside diphosphate kinase (NDK), conserved across bacteria to humans, synthesises NTP from NDP and ATP. The eukaryotic homologue, the NDPK, uses ATP to phosphorylate the tubulin-bound GDP to GTP for tubulin polymerisation. The bacterial cytokinetic protein FtsZ, which is the tubulin homologue, also uses GTP for polymerisation. Therefore, we examined whether NDK can interact with FtsZ to convert FtsZ-bound GDP and/or free GDP to GTP to trigger FtsZ polymerisation. Methods Recombinant and native NDK and FtsZ proteins of Mycobacterium smegmatis and Mycobacterium tuberculosis were used as the experimental samples. FtsZ polymersation was monitored using 90 degrees light scattering and FtsZ polymer pelleting assays. The gamma 32P-GTP synthesised by NDK from GDP and gamma 32P-ATP was detected using thin layer chromatography and quantitated using phosphorimager. The FtsZ bound P-32-GTP was quantitated using phosphorimager, after UV-crosslinking, followed by SDS-PAGE. The NDK-FtsZ interaction was determined using Ni2+-NTA-pulldown assay and co-immunoprecipitation of the recombinant and native proteins in vitro and ex vivo, respectively. Results NDK triggered instantaneous polymerisation of GDP-precharged recombinant FtsZ in the presence of ATP, similar to the polymerisation of recombinant FtsZ (not GDP-precharged) upon the direct addition of GTP. Similarly, NDK triggered polymerisation of recombinant FtsZ (not GDP-precharged) in the presence of free GDP and ATP as well. Mutant NDK, partially deficient in GTP synthesis from ATP and GDP, triggered low level of polymerisation of MsFtsZ, but not of MtFtsZ. As characteristic of NDK's NTP substrate non-specificity, it used CTP, TTP, and UTP also to convert GDP to GTP, to trigger FtsZ polymerisation. The NDK of one mycobacterial species could trigger the polymerisation of the FtsZ of another mycobacterial species. Both the recombinant and the native NDK and FtsZ showed interaction with each other in vitro and ex vivo, alluding to the possibility of direct phosphorylation of FtsZ-bound GDP by NDK. Conclusion Irrespective of the bacterial species, NDK interacts with FtsZ in vitro and ex vivo and, through the synthesis of GTP from FtsZ-bound GDP and/or free GDP, and ATP (CTP/TTP/UTP), triggers FtsZ polymerisation. The possible biological context of this novel activity of NDK is presented.
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Despite compromised T cell antigen receptor (TCR) signaling, mice in which tyrosine 136 of the adaptor linker for activation of T cells (LAT) was constitutively mutated (Lat(Y136F) mice) accumulate CD4(+) T cells that trigger autoimmunity and inflammation. Here we show that equipping postthymic CD4(+) T cells with LATY136F molecules or rendering them deficient in LAT molecules triggers a lymphoproliferative disorder dependent on prior TCR engagement. Therefore, such disorders required neither faulty thymic T cell maturation nor LATY136F molecules. Unexpectedly, in CD4(+) T cells recently deprived of LAT, the proximal triggering module of the TCR induced a spectrum of protein tyrosine phosphorylation that largely overlapped the one observed in the presence of LAT. The fact that such LAT-independent signals result in lymphoproliferative disorders with excessive cytokine production demonstrates that LAT constitutes a key negative regulator of the triggering module and of the LAT-independent branches of the TCR signaling cassette.
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Background: Post-rest contraction (PRC) of cardiac muscle provides indirect information about the intracellular calcium handling. Objective: Our aim was to study the behavior of PRC, and its underlying mechanisms, in rats with myocardial infarction. Methods: Six weeks after coronary occlusion, the contractility of papillary muscles (PM) obtained from sham-operated (C, n = 17), moderate infarcted (MMI, n = 10) and large infarcted (LMI, n = 14) rats was evaluated, following rest intervals of 10 to 60 seconds before and after incubation with lithium chloride (Li+) substituting sodium chloride or ryanodine (Ry). Protein expression of SR Ca(2+)-ATPase (SERCA2), Na+/Ca2+ exchanger (NCX), phospholamban (PLB) and phospho-Ser(16)-PLB were analyzed by Western blotting. Results: MMI exhibited reduced PRC potentiation when compared to C. Opposing the normal potentiation for C, post-rest decays of force were observed in LMI muscles. In addition, Ry blocked PRC decay or potentiation observed in LMI and C; Li+ inhibited NCX and converted PRC decay to potentiation in LMI. Although MMI and LMI presented decreased SERCA2 (72 +/- 7% and 47 +/- 9% of Control, respectively) and phospho-Ser(16)-PLB (75 +/- 5% and 46 +/- 11%, respectively) protein expression, overexpression of NCX (175 +/- 20%) was only observed in LMI muscles. Conclusion: Our results showed, for the first time ever, that myocardial remodeling after MI in rats may change the regular potentiation to post-rest decay by affecting myocyte Ca(2+) handling proteins. (Arq Bras Cardiol 2012;98(3):243-251)
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The paper deals with the problem of (the often supposedly impossible) conversion to “Hinduism”. I start with an outline of what I call the ‘no conversion possible’ paradigm, and briefl y point to the lack of refl ection on acceptance of converts in most theories of religious conversion. Then, two examples are presented: Firstly, I consider conversion to ISKCON and the discourse on the Hare Krishna movement’s Hinduness. Secondly, I give a brief outline of the globalsanatana dharmamovement as inaugurated by Satguru Siva Subramuniyaswami, a converted American Hindu based in Hawai’i. In the conclusion, I refl ect on (civic) social capital and engagement in global networks as a means to gain acceptance as converts to Hinduism. I argue in line with Stepick, Rey and Mahler (2009) that the religious movements’ civic engagement (in these cases engagement in favour of the Indian diasporic communities and of Hindus in India) provides a means for the individual, non-Indian converts to acquire the social capital that is necessary for gaining acceptance as ‘Hindus’ in certain contexts.
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LatLongConverter converts positions from geodetic system to Gauss-Krüger or UTM coordinates. This program is distributed as freeware for the operating systems Microsoft Windows, Apple OS X and Linux.
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Resistance to organophosphorus (OP) insecticides is associated with decreased carboxylesterase activity in several insect species. It has been proposed that the resistance may be the result of a mutation in a carboxylesterase that simultaneously reduces its carboxylesterase activity and confers an OP hydrolase activity (the “mutant ali-esterase hypothesis”). In the sheep blowfly, Lucilia cuprina, the association is due to a change in a specific esterase isozyme, E3, which, in resistant flies, has a null phenotype on gels stained using standard carboxylesterase substrates. Here we show that an OP-resistant allele of the gene that encodes E3 differs at five amino acid replacement sites from a previously described OP-susceptible allele. Knowledge of the structure of a related enzyme (acetylcholinesterase) suggests that one of these substitutions (Gly137 → Asp) lies within the active site of the enzyme. The occurrence of this substitution is completely correlated with resistance across 15 isogenic strains. In vitro expression of two natural and two synthetic chimeric alleles shows that the Asp137 substitution alone is responsible for both the loss of E3’s carboxylesterase activity and the acquisition of a novel OP hydrolase activity. Modeling of Asp137 in the homologous position in acetylcholinesterase suggests that Asp137 may act as a base to orientate a water molecule in the appropriate position for hydrolysis of the phosphorylated enzyme intermediate.
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A study was made of the effects of 5-hydroxytryptamine (5HT) on homomeric neuronal nicotinic receptors (nAcChoR) expressed in Xenopus oocytes after injection of cDNA encoding the wild-type chicken alpha(7) subunit. Acetylcholine (AcCho) elicited large currents (IAcCho) that were reduced by 5HT in a reversible and dose-dependent manner, with a half-inhibitory concentration (IC50) of 56 microM and a Hill coefficient (nH) of 1.2. The inhibition of IAcCho by 5HT was noncompetitive and voltage independent, a behavior incompatible with a channel blockade mechanism. 5HT alone did not elicit membrane currents in oocytes injected with the wild-type alpha(7) subunit cDNA. In contrast, 5HT elicited membrane currents (I5HT) in oocytes injected with cDNA encoding an alpha(7) mutant subunit with a threonine-for-leucine-247 substitution (L247T alpha(7)). I5HT was inhibited by the potent nicotinic receptor blockers alpha-bungarotoxin (100 nM) and methyllycaconitine (1 microM). Furthermore, the characteristics of I5HT, including its voltage dependence, were similar to those of IAcCho. The 5HT dose-I5HT response gave an apparent dissociation constant EC50 of 23.5 microM and a Hill coefficient nH of 1.7, which were not modified by the presence of AcCho. Similarly, the apparent affinity of L247T alpha(7) for AcCho as well as its cooperativity were not influenced by 5HT, indicating a lack of mutual interactions between 5HT and AcCho. These results show that 5HT is a potent noncompetitive antagonist of neuronal alpha(7) nAcChoR, but it becomes a noncompetitive agonist following mutation of the highly conserved leucine residue 247 located in the channel domain M2.
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The RecBCD enzyme of Escherichia coli promotes recombination preferentially at chi nucleotide sequences and has in vivo helicase and strong duplex DNA exonuclease (exoV) activities. The enzyme without the RecD subunit, as in a recD null mutant, promotes recombination efficiently but independently of chi and has no nucleolytic activity. Employing phage lambda red gam crosses, phage T4 2- survival measurements, and exoV assays, it is shown that E. coli cells in which RecBCD has extensive opportunity to interact with linear chi-containing DNA (produced by rolling circle replication of a plasmid with chi or by bleomycin-induced fragmentation of the cellular chromosome) acquire the phenotype of a recD mutant and maintain this for approximately 2 h. It is concluded that RecBCD is converted into RecBC during interaction with chi by irreversible inactivation of RecD. After conversion, the enzyme is released and initiates recombination on other DNA molecules in a chi-independent fashion. Overexpression of recD+ (from a plasmid) prevented the phenotypic change and providing RecD after the change restored chi-stimulated recombination. The observed recA+ dependence of the downregulation of exoV could explain the previously noted "reckless" DNA degradation of recA mutants. It is proposed that chi sites are regulatory elements for the RecBCD to RecBC switch and thereby function as cis- and trans-acting stimulators of RecBC-dependent recombination.
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src and erbB are two tyrosine kinase-encoding oncogenes carried by retroviruses, which have distinct disease specificities. The former induces predominantly sarcomas, and the latter, leukemias. Src and ErbB have similar catalytic domains but have very different regulatory domains. A wealth of information exists concerning how different regulatory domains [Src homology 2 (SH2) and SH3 domains and autophosphorylation sites] control substrate and disease specificities. Whether the catalytic domain helps determine these specificities remains to be explored. Here we show that the Src catalytic domain is enzymatically active when substituted into the ErbB backbone and interacts with the ErbB regulatory domain. This ErbB/Src chimera displays autophosphorylation and substrate phosphorylation patterns different from those of both Src and ErbB. Neither SH2 and SH3 nor autophosphorylation sites are required for the Src catalytic domain to exert its fibroblast transforming ability. Most significantly, the catalytic domain can convert erbB from a leukemogenic oncogene into a sarcomagenic oncogene, suggesting that the leukemogenic determinants in part reside within the ErbB catalytic domain.
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Bound in blindstamped brown cloth.
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Published anonymously by Sarah Sheppard. Cf. Halkett & Laing (2nd ed.)
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Mode of access: Internet.
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Mode of access: Internet.
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This document provides a review of international and national practices in investment decision support tools in road asset management. Efforts were concentrated on identifying analytic frameworks, evaluation methodologies and criteria adopted by current tools. Emphasis was also given to how current approaches support Triple Bottom Line decision-making. Benefit Cost Analysis and Multiple Criteria Analysis are principle methodologies in supporting decision-making in Road Asset Management. The complexity of the applications shows significant differences in international practices. There is continuing discussion amongst practitioners and researchers regarding to which one is more appropriate in supporting decision-making. It is suggested that the two approaches should be regarded as complementary instead of competitive means. Multiple Criteria Analysis may be particularly helpful in early stages of project development, say strategic planning. Benefit Cost Analysis is used most widely for project prioritisation and selecting the final project from amongst a set of alternatives. Benefit Cost Analysis approach is useful tool for investment decision-making from an economic perspective. An extension of the approach, which includes social and environmental externalities, is currently used in supporting Triple Bottom Line decision-making in the road sector. However, efforts should be given to several issues in the applications. First of all, there is a need to reach a degree of commonality on considering social and environmental externalities, which may be achieved by aggregating the best practices. At different decision-making level, the detail of consideration of the externalities should be different. It is intended to develop a generic framework to coordinate the range of existing practices. The standard framework will also be helpful in reducing double counting, which appears in some current practices. Cautions should also be given to the methods of determining the value of social and environmental externalities. A number of methods, such as market price, resource costs and Willingness to Pay, are found in the review. The use of unreasonable monetisation methods in some cases has discredited Benefit Cost Analysis in the eyes of decision makers and the public. Some social externalities, such as employment and regional economic impacts, are generally omitted in current practices. This is due to the lack of information and credible models. It may be appropriate to consider these externalities in qualitative forms in a Multiple Criteria Analysis. Consensus has been reached in considering noise and air pollution in international practices. However, Australia practices generally omitted these externalities. Equity is an important consideration in Road Asset Management. The considerations are either between regions, or social groups, such as income, age, gender, disable, etc. In current practice, there is not a well developed quantitative measure for equity issues. More research is needed to target this issue. Although Multiple Criteria Analysis has been used for decades, there is not a generally accepted framework in the choice of modelling methods and various externalities. The result is that different analysts are unlikely to reach consistent conclusions about a policy measure. In current practices, some favour using methods which are able to prioritise alternatives, such as Goal Programming, Goal Achievement Matrix, Analytic Hierarchy Process. The others just present various impacts to decision-makers to characterise the projects. Weighting and scoring system are critical in most Multiple Criteria Analysis. However, the processes of assessing weights and scores were criticised as highly arbitrary and subjective. It is essential that the process should be as transparent as possible. Obtaining weights and scores by consulting local communities is a common practice, but is likely to result in bias towards local interests. Interactive approach has the advantage in helping decision-makers elaborating their preferences. However, computation burden may result in lose of interests of decision-makers during the solution process of a large-scale problem, say a large state road network. Current practices tend to use cardinal or ordinal scales in measure in non-monetised externalities. Distorted valuations can occur where variables measured in physical units, are converted to scales. For example, decibels of noise converts to a scale of -4 to +4 with a linear transformation, the difference between 3 and 4 represents a far greater increase in discomfort to people than the increase from 0 to 1. It is suggested to assign different weights to individual score. Due to overlapped goals, the problem of double counting also appears in some of Multiple Criteria Analysis. The situation can be improved by carefully selecting and defining investment goals and criteria. Other issues, such as the treatment of time effect, incorporating risk and uncertainty, have been given scant attention in current practices. This report suggested establishing a common analytic framework to deal with these issues.