26 research outputs found

    Protective Effects of Pyruvic Acid Salt Against Lithium Toxicity andOxidative Damage in Human Blood Mononuclear Cells

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    Purpose: Aim of present work was to study cytoprotective properties of lithium pyruvate, as a prospective pharmacological agent. Pyruvate has a lot of potential benefits due to positive influence on cell metabolism. Lithium is “gold-standard” mood-stabilizer. Combination of both may lead advantages. Methods: Lithium pyruvate was tested as cytoprotector on human blood mononuclears under induced oxidative stress. Cells were obtained from healthy donors and patients with alcoholism. The detection of cell viability, apoptosis and determination of oxidative stress level were conducted by flow cytometry. Results: Lithium pyruvate showed excellent cytoprotective properties in normal and oxidation conditions. This effect was independent from cell donor health status. It was shown on cells from healthy donors and alcoholics patients. Conclusion: Obtained results allow considering lithium pyruvate as potential normothymic agents (mood stabilizer) with excellent cytoprotective properties

    Protective Effects of Pyruvic Acid Salt Against Lithium Toxicity andOxidative Damage in Human Blood Mononuclear Cells

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    Purpose: Aim of present work was to study cytoprotective properties of lithium pyruvate, as a prospective pharmacological agent. Pyruvate has a lot of potential benefits due to positive influence on cell metabolism. Lithium is “gold-standard” mood-stabilizer. Combination of both may lead advantages. Methods: Lithium pyruvate was tested as cytoprotector on human blood mononuclears under induced oxidative stress. Cells were obtained from healthy donors and patients with alcoholism. The detection of cell viability, apoptosis and determination of oxidative stress level were conducted by flow cytometry. Results: Lithium pyruvate showed excellent cytoprotective properties in normal and oxidation conditions. This effect was independent from cell donor health status. It was shown on cells from healthy donors and alcoholics patients. Conclusion: Obtained results allow considering lithium pyruvate as potential normothymic agents (mood stabilizer) with excellent cytoprotective properties

    Exploring, Refining, and Validating the Paradynamics QM/MM Sampling

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    The performance of the paradynamics (PD) reference potential approach in QM/MM calculations is examined. It is also clarified that, in contrast to some possible misunderstandings, this approach provides a rigorous strategy for QM/MM free energy calculations. In particular, the PD approach provides a gradual and controlled way of improving the evaluation of the free energy perturbation associated with moving from the EVB reference potential to the target QM/MM surface. This is achieved by moving from the linear response approximation to the full free energy perturbation approach in evaluating the free energy changes. We also present a systematic way of improving the reference potential by using Gaussian-based correction potentials along a reaction coordinate. In parallel, we review other recent adaptations of the reference potential approach, emphasizing and demonstrating the advantage of using the EVB potential as a reference potential, relative to semiempirical QM/MM molecular orbital potentials. We also compare the PD results to those obtained by direct calculations of the potentials of the mean force (PMF). Additionally, we propose a way of accelerating the PMF calculations by using Gaussian-based negative potentials along the reaction coordinate (which are also used in the PD refinement). Finally, we discuss performance of the PD and the metadynamics approaches in ab initio QM/MM calculations and emphasize the advantage of using the PD approach

    Molecular Origin of Mechanical Sensitivity of the Reaction Rate in Anthracene Cyclophane Isomerization Reveals Structural Motifs for Rational Design of Mechanophores

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    The observed pressure sensitivity of the isomerization reaction rate of bis-anthracene cyclophane photoisomer has attracted significant attention in the rational design of mechanically sensitive materials. However, the molecular origin of this sensitivity remains unclear. We developed an ab initio molecular model to quantify the effect of pressure on the reaction rate and to elucidate its molecular origin. Pressure-induced deformations and changes along the reaction free-energy surfaces are estimated from ab initio molecular dynamics trajectories. Our model predicts a barrier reduction of ∼2 kcal/mol at 0.9 GPa (in agreement with experiment). The barrier reduction is linear in the low-pressure regime (up to 2 GPa) but has a nonlinear dependence at higher pressures. We find that pressure alters the reaction path and that the mechanical sensitivity of the reaction rate is caused by an uneven distribution of the free-energy increase along the reaction surface. The uneven distribution primarily results from destabilization of the reactant, which has a lower mechanical rigidity along a particular deformation mode (flattening of anthracene rings as they are pushed toward each other in the cyclophane framework). Exploiting similar structural motifs to maximize rigidity differences along the reaction coordinate represents a promising rational design strategy

    Quantifying the Risks of Asparagine Deamidation and Aspartate Isomerization in Biopharmaceuticals by Computing Reaction Free-Energy Surfaces

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    Early identification of asparagine deamidation and aspartate isomerization degradation sites can facilitate the successful development of biopharmaceuticals. Several knowledge-based models have been proposed to assess these degradation risks. In this study, we propose a physics-based approach to identify the degradation sites on the basis of the free-energy barriers along the prechemical conformational step and the chemical reaction pathway. These contributions are estimated from classical and quantum mechanics/molecular mechanics molecular dynamics simulations. The computed barriers are compared to those for reference reactions in water within GNG and GDG sequence motifs in peptides (which demonstrate the highest degradation rates). Two major factors decreasing the degradation rates relative to the reference reactions are steric hindrance toward accessing reactive conformations and replacement of water by less polar side chains in the solvation shell of transition states. Among the potential degradation sites in the complementarity-determining region of trastuzumab and between two DK sites in glial cell-derived neurotropic factor, this method identified N<sup>30</sup>T, N<sup>55</sup>G, D<sup>102</sup>G, and D<sup>95</sup>K, respectively, in agreement with experiments. This approach can be incorporated in early computational screening of chemical degradation sites in biopharmaceuticals

    Quantifying the Mechanism of Phosphate Monoester Hydrolysis in Aqueous Solution by Evaluating the Relevant Ab Initio QM/MM Free-Energy Surfaces

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    Understanding the nature of the free-energy surfaces for phosphate hydrolysis is a prerequisite for understanding the corresponding key chemical reactions in biology. Here, the challenge has been to move to careful ab initio QM/MM (QM­(ai)/MM) free-energy calculations, where obtaining converging results is very demanding and computationally expensive. This work describes such calculations, focusing on the free-energy surface for the hydrolysis of phosphate monoesters, paying special attention to the comparison between the one water (1W) and two water (2W) paths for the proton-transfer (PT) step. This issue has been explored before by energy minimization with implicit solvent models and by nonsystematic QM/MM energy minimization, as well as by nonsystematic free-energy mapping. However, no study has provided the needed reliable 2D (3D) surfaces that are necessary for reaching concrete conclusions. Here we report a systematic evaluation of the 2D (3D) free-energy maps for several relevant systems, comparing the results of QM­(ai)/MM and QM­(ai)/implicit solvent surfaces, and provide an advanced description of the relevant energetics. It is found that the 1W path for the hydrolysis of the methyl diphosphate (MDP) trianion is 6–9 kcal/mol higher than that the 2W path. This difference becomes slightly larger in the presence of the Mg<sup>2+</sup> ion because this ion reduces the p<i>K</i><sub>a</sub> of the conjugated acid form of the phosphate oxygen that accepts the proton. Interestingly, the BLYP approach (which has been used extensively in some studies) gives a much smaller difference between the 1W and 2W activation barriers. At any rate, it is worth pointing out that the 2W transition state for the PT is not much higher that the common plateau that serves as the starting point of both the 1W and 2W PT paths. Thus, the calculated catalytic effects of proteins based on the 2W PT mechanistic model are not expected to be different from the catalytic effects predicted using the 1W PT mechanistic model, which was calibrated on the observed barrier in solution and in which the TS charge distribution was similar to the that of the plateau (as was done in all of our previous EVB studies)

    The mitochondria-targeted antioxidants and remote kidney preconditioning ameliorate brain damage through kidney-to-brain cross-talk.

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    BACKGROUND: Many ischemia-induced neurological pathologies including stroke are associated with high oxidative stress. Mitochondria-targeted antioxidants could rescue the ischemic organ by providing specific delivery of antioxidant molecules to the mitochondrion, which potentially suffers from oxidative stress more than non-mitochondrial cellular compartments. Besides direct antioxidative activity, these compounds are believed to activate numerous protective pathways. Endogenous anti-ischemic defense may involve the very powerful neuroprotective agent erythropoietin, which is mainly produced by the kidney in a redox-dependent manner, indicating an important role of the kidney in regulation of brain ischemic damage. The goal of this study is to track the relations between the kidney and the brain in terms of the amplification of defense mechanisms during SkQR1 treatment and remote renal preconditioning and provide evidence that the kidney can generate signals inducing a tolerance to oxidative stress-associated brain pathologies. METHODOLOGY/PRINCIPAL FINDINGS: We used the cationic plastoquinone derivative, SkQR1, as a mitochondria-targeted antioxidant to alleviate the deleterious consequences of stroke. A single injection of SkQR1 before cerebral ischemia in a dose-dependent manner reduces infarction and improves functional recovery. Concomitantly, an increase in the levels of erythropoietin in urine and phosphorylated glycogen synthase kinase-3β (GSK-3β) in the brain was detected 24 h after SkQR1 injection. However, protective effects of SkQR1 were not observed in rats with bilateral nephrectomy and in those treated with the nephrotoxic antibiotic gentamicin, indicating the protective role of humoral factor(s) which are released from functional kidneys. Renal preconditioning also induced brain protection in rats accompanied by an increased erythropoietin level in urine and kidney tissue and P-GSK-3β in brain. Co-cultivation of SkQR1-treated kidney cells with cortical neurons resulted in enchanced phosphorylation of GSK-3β in neuronal cells. CONCLUSION: The results indicate that renal preconditioning and SkQR1-induced brain protection may be mediated through the release of EPO from the kidney

    Macrophage Phenotype in Combination with Tumor Microbiome Composition Predicts RCC Patients’ Survival: A Pilot Study

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    The identification of new prognostic markers of renal cell carcinoma (RCC) is an urgent problem in oncourology. To investigate the potential prognostic significance of tumor microbiome and stromal inflammatory markers, we studied a cohort of 66 patients with RCC (23 clear cell RCC, 19 papillary RCC and 24 chromophobe RCC). The microbiome was analyzed in tumor and normal tissue by 16S rRNA amplicon sequencing. Characterization of the tumor stroma was performed using immunohistochemistry. A significant difference in alpha diversity was demonstrated between normal kidney tissue and all types of RCC. Further, we demonstrated that the bacterial burden was higher in adjacent normal tissue than in a tumor. For the first time, we demonstrated a significant correlation between bacterial burden and the content of PU.1+ macrophages and CD66b+ neutrophils in kidney tumors. Tumors with high content of PU.1+ cells and CD66b+ cells in the stroma were characterized by a lower bacterial burden. In the tumors with high bacterial burden, the number of PU.1+ cells and CD66b+ was associated with a poor prognosis. The identified associations indicate the great prognostic potential of a combined tumor microbiome and stromal cell analysis
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