Antipig antibodies are a barrier to clinical xenotransplantation. We evaluated antibody binding of waitlisted renal transplant patients to 3 glycan knockout (KO) pig cells and class I swine leukocyte ...antigens (SLA).
Peripheral blood mononuclear cells from SLA identical wild type (WT), α1, 3-galactosyltransferase (GGTA1) KO, GGTA1/ cytidine monophosphate-N-acetylneuraminic acid hydroxylase (CMAH) KO, and GGTA1/ CMAH /b1,4 N-acetylgalactosaminyl transferase (B4GalNT2) KO pigs were screened for human antibody binding using flow cytometric crossmatch (FCXM). Sera from 820 patients were screened on GGTA1/CMAH/B4GalNT2 KO cells and a subset with elevated binding was evaluated further. FCXM was performed on SLA intact cells and GGTA1/SLA class I KO cells after depletion with WT pig RBCs to remove cell surface reactive antibodies, but leave SLA antibodies. Lastly, human and pig reactive antibodies were eluted and tested for cross-species binding and reactivity to single-antigen HLA beads.
Sequential glycan KO modifications significantly reduce antibody binding of waitlisted patients. Sera exhibiting elevated binding without reduction after depletion with WT RBCs demonstrate reduced binding to SLA class I KO cells. Human IgG, eluted from human and pig peripheral blood mononuclear cells, interacted across species and bound single-antigen HLA beads in common epitope-restricted patterns.
Many waitlisted patients have minimal xenoreactive antibody binding to the triple KO pig, but some HLA antibodies in sensitized patients cross-react with class I SLA. SLA class I is a target for genome editing in xenotransplantation.
Summary
Tooth wear in bruxing patients often results in a need for treatment with composite restorations. In some cases, bruxing patients receive an occlusal splint as a protective means as well. ...However, the wear between these opposing materials has not been investigated yet. The aim of this in vitro study was to assess the wear of different splint materials against resin composite materials. A two‐body wear test was conducted using the ACTA wear machine. The materials selected for this study were three composites used for direct restorations (Filtek Z250, CLEARFIL AP‐X, and Filtek Supreme XT) and four occlusal splints materials, viz. a polyamide resin (ThermoSens) an conventional (hand‐processed), milled and printed polymethylmethacrylate (PMMA). As antagonistic materials, stainless steel, Filtek Supreme XT and CLEARFIL AP‐X were used. The wear rate of the seven materials was determined after 200 000 cycles, using a profilometry. The rates were analysed using two‐way ANOVA and post hoc Tukey's tests. The wear rates were significantly higher for the conventional and milled PMMA materials than for all other materials (P < .001). The wear rates of printed PMMA and the polyamide resin were comparable to composite wear rates. The antagonist materials have minor or no influence on the amount of wear of the various splint materials (P < .001). In conclusion, different splint materials yielded different wear rates for all antagonist materials tested. Keeping in mind that this study is an experimental in vitro study, this finding enables practitioners to choose the splint material necessary according to their patients’ needs.
The kinetics of the FeB/Fe2B layers and diffusion zone at the surface of AISI 316 steels exposed to the powder-pack boriding process were studied in this work. FeB/Fe2B layers and diffusion zone ...measurements were taken at different temperatures and exposure times to validate diffusion-controlled growth during the boriding process. In order to obtain the boron diffusion coefficients at the FeB/Fe2B layers and diffusion zone, a mathematical model based on the mass balance at the growing interfaces was proposed. The activation energy values estimated for the FeB and Fe2B layers were 204 and 198kJmola degree 1 respectively. In addition, the activation energy value obtained for the diffusion zone was 116kJmola degree 1. The diffusion model was extended to estimate the FeB/Fe2B layer thicknesses, and the depth of the diffusion zone at the temperature of 1243K with 3 and 5h of exposure, based on the experimental parameters ascribed to the boriding process. Finally, the effects of the FeB/Fe2B growth and diffusion zone, on the weight gain of borided steels and on the instantaneous velocity of the interfaces were incorporated in the model.
MANGANESE AS ESSENTIAL AND TOXIC ELEMENT FOR PLANTS: TRANSPORT, ACCUMULATION AND RESISTANCE MECHANISMS Millaleo, R(Universidad de La Frontera Programa de Doctorado en Ciencias de Recursos Naturales); Reyes- Diaz, M(Universidad de La Frontera Center of Plant-Soil Interaction and Natural Resources Biotechnology Scientific and Technological Bioresource Nucleus (BIOREN),); Ivanov, A.G(University of Western Department of Biology and the Biotron) ...
Journal of soil science and plant nutrition,
2010, 2010-00-00, 20100001, Volume:
10, Issue:
4
Journal Article
Peer reviewed
Open access
Manganese is an essential element for plants, intervening in several metabolic processes, mainly in photosynthesis and as an enzyme antioxidant-cofactor. Nevertheless, an excess of this micronutrient ...is toxic for plants. Mn phytotoxicity is manifested in a reduction of biomass and photosynthesis, and biochemical disorders such as oxidative stress. Some studies on Mn toxicity and Mn translocation from soil to plant cells in Mn2+ form have demonstrated their importance under low pH and redox potential conditions in the soil. When Mn is inside the cells, mechanisms that can tolerate this toxicity are also observed, being important the compartmentalization of this metal in different organdíes of shoot and leaf plant cells. A key role of antioxidative systems in plants in relation to high Mn amounts has also been reported as a defense mechanism. The purpose of this review is to show the role of Mn as an essential micronutrient and as a toxic element to higher plants as well as to their transport and tolerance mechanisms. The forms and dynamics of this element in soils and the importance of the acidity for this dynamic and availability for plants are also given.
The influence of climate variability on Eastern Boundary Upwelling Ecosystems (EBUEs) is evident through changes in productivity and shifts in species' distributions, yet to date, metrics of ...upwelling variability appropriate for comparative ecosystem studies have yet to be implemented. Here, we present synoptic-scale upwelling indices to quantify inter-annual to decadal variations in Ekman transport, at temporal and spatial scales relevant to the biota of EBUEs, and apply them to the Benguela Upwelling System (BUS). From 1979 to 2015, interannual, decadal-scale, and unidirectional variability in upwelling was observed, including a significant recent decrease in upwelling in the northern BUS, and a significant increase on the Agulhas Bank. These trends are associated with changes in the number of upwelling days and events in these regions, and correspond to a shift in the meridional positioning of the South Atlantic High pressure system.
•Significant interannual, decadal, and spatial variability in upwelling in the Benguela Upwelling System (BUS)•Upwelling in the northern BUS has recently decreased, whereas it has increased on the Agulhas Bank, with no trend in the southern BUS•Temporal changes in upwelling are associated with shifts in the number of upwelling days and events in each region•Trends in upwelling correspond to meridional shifts in the position of the South Atlantic High pressure system
Hydrogen sulfide (H2S) participates in prokaryotic metabolism and is associated with several physiological functions in mammals. H2S reacts with oxidized thiol derivatives (i.e. disulfides and ...sulfenic acids) and thereby forms persulfides, which are plausible transducers of the H2S-mediated signaling effects. The one-cysteine peroxiredoxin alkyl hydroperoxide reductase E from Mycobacterium tuberculosis (MtAhpE–SH) reacts fast with hydroperoxides, forming a stable sulfenic acid (MtAhpE–SOH), which we chose here as a model to study the interactions between H2S and peroxiredoxins (Prx). MtAhpE–SOH reacted with H2S, forming a persulfide (MtAhpE–SSH) detectable by mass spectrometry. The rate constant for this reaction was (1.4 ± 0.2) × 103m−1 s−1 (pH 7.4, 25 °C), six times higher than that reported for the reaction with the main low-molecular-weight thiol in M. tuberculosis, mycothiol. H2S was able to complete the catalytic cycle of MtAhpE and, according to kinetic considerations, it could represent an alternative substrate in M. tuberculosis. MtAhpE–SSH reacted 43 times faster than did MtAhpE–SH with the unspecific electrophile 4,4′-dithiodipyridine, a disulfide that exhibits no preferential reactivity with peroxidatic cysteines, but MtAhpE–SSH was less reactive toward specific Prx substrates such as hydrogen peroxide and peroxynitrite. According to molecular dynamics simulations, this loss of specific reactivity could be explained by alterations in the MtAhpE active site. MtAhpE–SSH could transfer its sulfane sulfur to a low-molecular-weight thiol, a process likely facilitated by the low pKa of the leaving thiol MtAhpE–SH, highlighting the possibility that Prx participates in transpersulfidation. The findings of our study contribute to the understanding of persulfide formation and reactivity.
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•Study the influence of equivalence ratio and engine speed on cyclic variations.•Diagnostic model with temperature dependant properties.•Genetic algorithms applied to the analysis of ...the combustion inside an engine.•Automatic adjustment of the diagnostic parameters.•Application of the methodology to the study of the cyclic variability.
In this work a study of the influence of the fuel/air equivalence ratio and engine rotational speed on the cycle-to-cycle variations in combustion in a natural gas spark ignition engine is presented. The study considers both classic estimators of cyclic dispersion and a new one, based on the burned mass and burning rate. The engine experimental conditions were as follows: Intake pressure 0.5bar, while fuel/air equivalence ratio was changed from 1.0 to 0.63, and engine rotational speed was varied from 1000rpm to 2500rpm. For each equivalence ratio and engine speed, a diagnosis model is used to process the experimentally obtained combustion pressure data in order to provide combustion relevant results such as the mass burning rate at a cycle level. A procedure based on the use of genetic algorithms is used to obtain a very accurate and objective (without human intervention) adjustment of the optimum parameters needed for combustion diagnosis: angular positioning and pressure offset of the pressure register, dynamic compression ratio, and heat transfer coefficients. The model allows making the diagnosis of series of 830 consecutive engine cycles in an automatic way, increasing the objectivity of the combustion diagnosis. The paper focuses on using the values of the mass fraction burned computed from the pressure register and especially on the analysis of the combustion cycle to cycle variation in the natural gas fuelled engine. A new indicator for the study of cycle-to-cycle variations is proposed, i.e. the standard deviation of the mass fraction burning rate. The values of this new indicator are compared with other classic indicators, showing the same general trends. However, a deeper insight is provided on the combustion cyclic variation when the values of the new indicator are plotted as a function of the mass fraction burned, since this allows analyzing the cyclic variation along the combustion development in each cycle from a mass fraction burned of zero to one, with a relevant value at mass fraction burned of 0.5. More important is that the consideration of the dependence of the combustion variables (density, flame front surface, combustion speed) on the mass fraction burned allows ensemble averaging of all registered cycles for each value of mass fraction burned. This permits using the ensemble averaged mass fraction burning rate as an estimator of combustion speed.
The analysis of the general trends of cyclic dispersion when engine speed and equivalence ratio are modified (1000, 1750 and 2500rpm; 0.7, 0.8, 0.9 and 1.0) indicate that cycle-to-cycle variations show, as expected, a strong dependence on the engine rotational speed, increasing the variation with engine rpm. However, when the standard deviation of mass fraction burning rate is plotted as a function of mass fraction burned, there is a linear dependence on engine rpm, but only a very weak dependence on equivalence ratio. This means that the proposed estimator of cyclic dispersion is sensitive to only flow turbulent intensity and not to equivalence ratio.
Mitochondria are main sites of peroxynitrite formation. While at low concentrations mitochondrial peroxynitrite has been associated with redox signaling actions, increased levels can disrupt ...mitochondrial homeostasis and lead to pathology. Peroxiredoxin 3 is exclusively located in mitochondria, where it has been previously shown to play a major role in hydrogen peroxide reduction. In turn, reduction of peroxynitrite by peroxiredoxin 3 has been inferred from its protective actions against tyrosine nitration and neurotoxicity in animal models, but was not experimentally addressed so far. Herein, we demonstrate the human peroxiredoxin 3 reduces peroxynitrite with a rate constant of 1 × 107 M−1 s−1 at pH 7.8 and 25 °C. Reaction with hydroperoxides caused biphasic changes in the intrinsic fluorescence of peroxiredoxin 3: the first phase corresponded to the peroxidatic cysteine oxidation to sulfenic acid. Peroxynitrite in excess led to peroxiredoxin 3 hyperoxidation and tyrosine nitration, oxidative post-translational modifications that had been previously identified in vivo. A significant fraction of the oxidant is expected to react with CO2 and generate secondary radicals, which participate in further oxidation and nitration reactions, particularly under metabolic conditions of active oxidative decarboxylations or increased hydroperoxide formation. Our results indicate that both peroxiredoxin 3 and 5 should be regarded as main targets for peroxynitrite in mitochondria.
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•Human Prx3 rapidly reduces peroxynitrite.•Prx3 intrinsic fluorescence presents biphasic changes upon oxidation.•Peroxynitrite in excess leads to Prx3 nitration and hyperoxidation.•Both Prx3 and Prx5 are predicted to be main targets for mitochondrial peroxynitrite.
Gold nanoparticles were selectively attached to chemically functionalized surface sites on nitrogen-doped carbon (CN x ) nanotubes. A cationic polyelectrolyte was adsorbed on the surface of the ...nanotubes by electrostatic interaction between carboxyl groups on the chemically oxidized nanotube surface and polyelectrolyte chains. Negatively charged 10 nm gold nanoparticles from a gold colloid suspension were subsequently anchored to the surface of the nanotubes through the electrostatic interaction between the polyelectrolyte and the nanoparticles. This approach provides an efficient method to attach other nanostructures to carbon nanotubes and can be used as an illustrative detection of the functional groups on carbon nanotube surfaces.
Metacognition refers to the human capacity to access and monitor one's own mental states. Recent research suggests that this capacity expands to the social world, e.g., when individuals explicitly ...share their cognitive processes with others. Additionally, metacognition is also linked to cognitive flexibility, and the latter to ideologically radical behaviors. Indeed, the absence of control over one's own mental activity could be at the base of different phenomena linked to social cognition. We investigate the metacognitive capacity of individuals in relation to the radicality with which they make a moral choice (utilitarian vs. deontological). For this purpose, 76 participants were submitted to 24 hypothetical situations, with the aim of evaluating the consistency (i.e., the radicality) of their moral choices. Then, in an independent experimental session, we evaluated the participants' metacognitive efficiency. We managed to demonstrate that individual metacognition scores are correlated with the radicality of a moral choice. We discussed the impact and relevance of metacognition in ecological contexts, particularly where subjective evaluation of the environment involves individual choices with social consequences.
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