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‣ Evaluation of the effects of photodynamic therapy with phosphorus 31 magnetic resonance spectroscopy

Nishiwaki, M; Fujise, Y; Yoshida, T O; Matsuzawa, E; Nishiwaki, Y
Fonte: Nature Publishing Group Publicador: Nature Publishing Group
Tipo: Artigo de Revista Científica
Publicado em /04/1999 Português
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Magnetic resonance spectroscopy in situ was used to study changes in phosphorus 31 metabolism after photodynamic therapy (PDT) of transplanted HeLa cell tumours. Tumours were irradiated 2 h after administration of ATX-S10 (8-formyloximethylidene-7-hydroxy-3-ethenyl-2,7,12,18, tetramethyl-porphyrin-13,17-bispropionil aspartate), a new photosensitizer and chlorin derivative. Nuclear magnetic resonance spectra were measured prior to illumination and 1, 3, 7, 14, 21 and 28 days after PDT on each mouse. A drastic decrease in adenosine triphosphate (ATP) and a concomitant increase in inorganic phosphate (Pi) were evident on the first day after PDT in all cases. The β-ATP/total phosphate (P) ratio was 0.64 ± 0.29% (average ± s.d.) in complete response, 0.67 ± 0.30% in recurrence and 2.45 ± 0.93% in partial response. Comparison of this ratio to the histological findings revealed that the β-ATP/total P ratio reflects the HeLa cell tumours which survived PDT. In other words, partial response on the one hand was distinguished from complete response and recurrence on the other with this ratio 1 day after PDT (P < 0.05). In addition, the ratio of phosphomonoester (PME) to Pi rose beyond 1.0 when macroscopic recurrence occurred, while it stayed under 1.0 in complete response. This finding suggests that the recurrence of HeLa cell tumours can be detected by the PME/Pi ratio. © 1999 Cancer Research Campaign

‣ Pepper pectin methylesterase inhibitor protein CaPMEI1 is required for antifungal activity, basal disease resistance and abiotic stress tolerance

An, Soo Hyun; Sohn, Kee Hoon; Choi, Hyong Woo; Hwang, In Sun; Lee, Sung Chul; Hwang, Byung Kook
Fonte: Springer-Verlag Publicador: Springer-Verlag
Tipo: Artigo de Revista Científica
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Pectin is one of the main components of the plant cell wall that functions as the primary barrier against pathogens. Among the extracellular pectinolytic enzymes, pectin methylesterase (PME) demethylesterifies pectin, which is secreted into the cell wall in a highly methylesterified form. Here, we isolated and functionally characterized the pepper (Capsicum annuum L.) gene CaPMEI1, which encodes a pectin methylesterase inhibitor protein (PMEI), in pepper leaves infected by Xanthomonascampestris pv. vesicatoria (Xcv). CaPMEI1 transcripts are localized in the xylem of vascular bundles in leaf tissues, and pathogens and abiotic stresses can induce differential expression of this gene. Purified recombinant CaPMEI1 protein not only inhibits PME, but also exhibits antifungal activity against some plant pathogenic fungi. Virus-induced gene silencing of CaPMEI1 in pepper confers enhanced susceptibility to Xcv, accompanied by suppressed expression of some defense-related genes. Transgenic ArabidopsisCaPMEI1-overexpression lines exhibit enhanced resistance to Pseudomonas syringae pv. tomato, mannitol and methyl viologen, but not to the biotrophic pathogen Hyaloperonospora parasitica. Together, these results suggest that CaPMEI1, an antifungal protein...

‣ Folate Deficiency Induces In Vitro and Mouse Brain Region-Specific Downregulation of Leucine Carboxyl Methyltransferase-1 and Protein Phosphatase 2A Bα Subunit Expression that Correlate with Enhanced Tau Phosphorylation

Sontag, Jean-Marie; Nunbhakdi-Craig, Viyada; Montgomery, Lisa; Arning, Erland; Bottiglieri, Teodoro; Sontag, Estelle
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em 05/11/2008 Português
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Altered folate homeostasis is associated with many clinical and pathological manifestations in the CNS. Notably, folate-mediated one-carbon metabolism is essential for methyltransferase-dependent cellular methylation reactions. Biogenesis of protein phosphatase 2A (PP2A) holoenzyme containing the regulatory Bα subunit, a major brain tau phosphatase, is controlled by methylation. Here, we show that folate deprivation in neuroblastoma cells induces downregulation of PP2A leucine carboxyl methyltransferase-1 (LCMT-1) expression, resulting in progressive accumulation of newly-synthesized demethylated PP2A pools, concomitant loss of Bα, and ultimately cell death. These effects are further accentuated by overexpression of PP2A methylesterase (PME-1), but cannot be rescued by PME-1 knockdown. Overexpression of either LCMT-1 or Bα is sufficient to protect cells against the accumulation of demethylated PP2A, increased tau phosphorylation and cell death induced by folate starvation. Conversely, knockdown of either protein accelerates folate deficiency-evoked cell toxicity. Significantly, mice maintained for 2 months on low folate or folate-deficient diets have brain region-specific alterations in metabolites of the methylation pathway. Those are associated with downregulation of LCMT-1...

‣ Mapping hypoxia-induced bioenergetic rearrangements and metabolic signaling by 18O-assisted 31P NMR and 1H NMR spectroscopy

Pucar, Darko; Dzeja, Petras P.; Bast, Peter; Gumina, Richard J.; Drahl, Carmen; Lim, Lynette; Juranic, Nenad; Macura, Slobodan; Terzic, Andre
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em //2004 Português
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Brief hypoxia or ischemia perturbs energy metabolism inducing paradoxically a stress-tolerant state, yet metabolic signals that trigger cytoprotection remain poorly understood. To evaluate bioenergetic rearrangements, control and hypoxic hearts were analyzed with 18O-assisted 31P NMR and 1H NMR spectroscopy. The 18O-induced isotope shift in the 31P NMR spectrum of CrP, βADP and βATP was used to quantify phosphotransfer fluxes through creatine kinase and adenylate kinase. This analysis was supplemented with determination of energetically relevant metabolites in the phosphomonoester (PME) region of 31P NMR spectra, and in both aromatic and aliphatic regions of 1H NMR spectra. In control conditions, creatine kinase was the major phosphotransfer pathway processing high-energy phosphoryls between sites of ATP consumption and ATP production. In hypoxia, creatine kinase flux was dramatically reduced with a compensatory increase in adenylate kinase flux, which supported heart energetics by regenerating and transferring β- and γ-phosphoryls of ATP. Activation of adenylate kinase led to a build-up of AMP, IMP and adenosine, molecules involved in cardioprotective signaling. 31P and 1H NMR spectral analysis further revealed NADH and H+ scavenging by α-glycerophosphate dehydrogenase (αGPDH) and lactate dehydrogenase contributing to maintained glycolysis under hypoxia. Hypoxia-induced accumulation of α-glycerophosphate and nucleoside 5′-monophosphates...

‣ Exocytosis Precedes and Predicts the Increase in Growth in Oscillating Pollen Tubes[W]

McKenna, Sylvester T.; Kunkel, Joseph G.; Bosch, Maurice; Rounds, Caleb M.; Vidali, Luis; Winship, Lawrence J.; Hepler, Peter K.
Fonte: American Society of Plant Biologists Publicador: American Society of Plant Biologists
Tipo: Artigo de Revista Científica
Publicado em /10/2009 Português
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We examined exocytosis during oscillatory growth in lily (Lilium formosanum and Lilium longiflorum) and tobacco (Nicotiana tabacum) pollen tubes using three markers: (1) changes in cell wall thickness by Nomarski differential interference contrast (DIC), (2) changes in apical cell wall fluorescence in cells stained with propidium iodide (PI), and (3) changes in apical wall fluorescence in cells expressing tobacco pectin methyl esterase fused to green fluorescent protein (PME-GFP). Using PI fluorescence, we quantified oscillatory changes in the amount of wall material from both lily and tobacco pollen tubes. Measurement of wall thickness by DIC was only possible with lily due to limitations of microscope resolution. PME-GFP, a direct marker for exocytosis, only provides information in tobacco because its expression in lily causes growth inhibition and cell death. We show that exocytosis in pollen tubes oscillates and leads the increase in growth rate; the mean phase difference between exocytosis and growth is –98° ± 3° in lily and –124° ± 4° in tobacco. Statistical analyses reveal that the anticipatory increase in wall material predicts, to a high degree, the rate and extent of the subsequent growth surge. Exocytosis emerges as a prime candidate for the initiation and regulation of oscillatory pollen tube growth.

‣ An N log N approximation based on the natural organization of biomolecules for speeding up the computation of long range interactions

Anandakrishnan, Ramu; Onufriev, Alexey V.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /03/2010 Português
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Presented here is a method, the hierarchical charge partitioning (HCP) approximation, for speeding up computation of pairwise electrostatic interactions in biomolecular systems. The approximation is based on multiple levels of natural partitioning of biomolecular structures into a hierarchical set of its constituent structural components. The charge distribution in each component is systematically approximated by a small number of point charges, which, for the highest level component, are much fewer than the number of atoms in the component. For short distances from the point of interest, the HCP uses the full set of atomic charges available. For long distance interactions, the approximate charge distributions with smaller sets of charges are used instead. For a structure consisting of N charges, the computational cost of computing the pairwise interactions via the HCP scales as O(N log N), under assumptions about the structural organization of biomolecular structures generally consistent with reality. A proof-of-concept implementation of the HCP shows that for large structures it can lead to speed-up factors of up to several orders of magnitude relative to the exact pairwise O(N2) all-atom computation used as a reference. For structures with more than 2–3 thousand atoms the relative accuracy of the HCP (relative root-mean-square force error per atom)...

‣ Recovery of heat shock-triggered released apoplastic Ca2+ accompanied by pectin methylesterase activity is required for thermotolerance in soybean seedlings

Wu, Hui-Chen; Hsu, Shih-Feng; Luo, Dan-Li; Chen, Shiang-Jiuun; Huang, Wen-Dar; Lur, Huu-Sheng; Jinn, Tsung-Luo
Fonte: Oxford University Press Publicador: Oxford University Press
Tipo: Artigo de Revista Científica
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Synthesis of heat shock proteins (HSPs) in response to heat shock (HS) is essential for thermotolerance. The effect of a Ca2+ chelator, EGTA, was investigated before a lethal HS treatment in soybean (Glycine max) seedlings with acquired thermotolerance induced by preheating. Such seedlings became non-thermotolerant with EGTA treatment. The addition of Ca2+, Sr2+ or Ba2+ to the EGTA-treated samples rescued the seedlings from death by preventing the increased cellular leakage of electrolytes, amino acids, and sugars caused by EGTA. It was confirmed that EGTA did not affect HSP accumulation and physiological functions but interfered with the recovery of HS-released Ca2+ concentration which was required for thermotolerance. Pectin methylesterase (PME, EC 3.1.1.11), a cell wall remodelling enzyme, was activated in response to HS, and its elevated activity caused an increased level of demethylesterified pectin which was related to the recovery of the HS-released Ca2+ concentration. Thus, the recovery of HS-released Ca2+ in Ca2+-pectate reconstitution through PME activity is required for cell wall remodelling during HS in soybean which, in turn, retains plasma membrane integrity and co-ordinates with HSPs to confer thermotolerance.

‣ Sexuality research in India: An update

Prakash, Om; Rao, T. S. Sathyanarayana
Fonte: Medknow Publications Publicador: Medknow Publications
Tipo: Artigo de Revista Científica
Publicado em /01/2010 Português
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This review provides the available evidence on sexual dysfunctions in India. Most of the studies have concentrated on male sexual dysfunction and hardly a few have voiced the sexual problems in females. Erectile dysfunction (ED), premature ejaculation (PME) and combinations of ED and PME appear to be main dysfunctions reported in males. Dhat syndrome remains an important diagnosis reported in studies from North India. There is a paucity of literature on management issues with an emergent need to conduct systematic studies in this neglected area so that the concerns of these patients can be properly dealt with.

‣ Structural, Dynamic, and Electrostatic Properties of Fully Hydrated DMPC Bilayers From Molecular Dynamics Simulations Accelerated with Graphical Processing Units (GPUs)

Ganesan, Narayan; Bauer, Brad A.; Lucas, Timothy R.; Patel, Sandeep; Taufer, Michela
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
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We present results of molecular dynamics simulations of fully hydrated DMPC bilayers performed on graphics processing units (GPUs) using current state-of-the-art non-polarizable force fields and a local GPU-enabled molecular dynamics code named FEN ZI. We treat the conditionally convergent electrostatic interaction energy exactly using the Particle Mesh Ewald method (PME) for solution of Poisson’s Equation for the electrostatic potential under periodic boundary conditions. We discuss elements of our implementation of the PME algorithm on GPUs as well as pertinent performance issues. We proceed to show results of simulations of extended lipid bilayer systems using our program, FEN ZI. We performed simulations of DMPC bilayer systems consisting of 17004, 68484 and 273936 atoms in explicit solvent. We present bilayer structural properties (atomic number densities, electron density profiles), deuterium order parameters (SCD), electrostatic properties (dipole potential, water dipole moments), and orientational properties of water. Predicted properties demonstrate excellent agreement with experiment and previous all-atom molecular dynamics simulations. We observe no statistically significant differences in calculated structural or electrostatic properties for different system sizes...

‣ Synthesis, Assembly, and Characterization of Monolayer Protected Gold Nanoparticle Films for Protein Monolayer Electrochemistry

Doan, Tran T.; Freeman, Michael H.; Schmidt, Adrienne R.; Nguyen, Natalie D. T.; Leopold, Michael C.
Fonte: MyJove Corporation Publicador: MyJove Corporation
Tipo: Artigo de Revista Científica
Publicado em 04/10/2011 Português
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Colloidal gold nanoparticles protected with alkanethiolate ligands called monolayer protected gold clusters (MPCs) are synthesized and subsequently incorporated into film assemblies that serve as adsorption platforms for protein monolayer electrochemistry (PME). PME is utilized as the model system for studying electrochemical properties of redox proteins by confining them to an adsorption platform at a modified electrode, which also serves as a redox partner for electron transfer (ET) reactions. Studies have shown that gold nanoparticle film assemblies of this nature provide for a more homogeneous protein adsorption environment and promote ET without distance dependence compared to the more traditional systems modified with alkanethiol self-assembled monolayers (SAM).1-3 In this paper, MPCs functionalized with hexanethiolate ligands are synthesized using a modified Brust reaction4 and characterized with ultraviolet visible (UV-Vis) spectroscopy, transmission electron microscopy (TEM), and proton (1H) nuclear magnetic resonance (NMR). MPC films are assembled on SAM modified gold electrode interfaces by using a "dip cycle" method of alternating MPC layers and dithiol linking molecules. Film growth at gold electrode is tracked electrochemically by measuring changes to the double layer charging current of the system. Analogous films assembled on silane modified glass slides allow for optical monitoring of film growth and cross-sectional TEM analysis provides an estimated film thickness. During film assembly...

‣ Calculation of the Absolute Free Energy of Binding and Related Entropies with the HSMD-TI Method: The FKBP12-L8 Complex

General, Ignacio J.; Dragomirova, Ralitsa; Meirovitch, Hagai
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em 27/10/2011 Português
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The hypothetical scanning molecular dynamics (HSMD) method is used here for calculating the absolute free energy of binding, ΔA0 of the complex of the protein FKBP12 with the ligand SB2 (also denoted L8) – a system that has been studied previously for comparing the performance of different methods. Our preliminary study suggests that considering long-range electrostatics is imperative even for a hydrophobic ligand such as L8. Therefore the system is modeled by the AMBER force field using Particle Mesh Ewald (PME). HSMD consists of three stages applied to both the ligand-solvent and ligand-protein systems. (1) A small set of system configurations (frames) is extracted from an MD trajectory. (2) The entropy of the ligand in each frame is calculated by a reconstruction procedure. (3) The contribution of water and protein to ΔA0 is calculated for each frame by gradually increasing the ligand-environment interactions from zero to their full value using thermodynamic integration (TI). Unlike the conventional methods, the structure of the ligand is kept fixed during TI, and HSMD is thus free from the end-point problem encountered with the double annihilation method (DAM); therefore, the need for applying restraints is avoided. Furthermore...

‣ A Homozygous Mutation in KCTD7 Links Neuronal Ceroid Lipofuscinosis to the Ubiquitin-Proteasome System

Staropoli, John F.; Karaa, Amel; Lim, Elaine T.; Kirby, Andrew; Elbalalesy, Naser; Romansky, Stephen G.; Leydiker, Karen B.; Coppel, Scott H.; Barone, Rosemary; Xin, Winnie; MacDonald, Marcy E.; Abdenur, Jose E.; Daly, Mark J.; Sims, Katherine B.
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Publicado em 13/07/2012 Português
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Neuronal ceroid lipofuscinosis (NCL) is a genetically heterogeneous group of lysosomal diseases that collectively compose the most common Mendelian form of childhood-onset neurodegeneration. It is estimated that ∼8% of individuals diagnosed with NCL by conservative clinical and histopathologic criteria have been ruled out for mutations in the nine known NCL-associated genes, suggesting that additional genes remain unidentified. To further understand the genetic underpinnings of the NCLs, we performed whole-exome sequencing on DNA samples from a Mexican family affected by a molecularly undefined form of NCL characterized by infantile-onset progressive myoclonic epilepsy (PME), vision loss, cognitive and motor regression, premature death, and prominent NCL-type storage material. Using a recessive model to filter the identified variants, we found a single homozygous variant, c.550C>T in KCTD7, that causes a p.Arg184Cys missense change in potassium channel tetramerization domain-containing protein 7 (KCTD7) in the affected individuals. The mutation was predicted to be deleterious and was absent in over 6,000 controls. The identified variant altered the localization pattern of KCTD7 and abrogated interaction with cullin-3, a ubiquitin-ligase component and known KCTD7 interactor. Intriguingly...

‣ Circumventing Cellular Control of PP2A by Methylation Promotes Transformation in an Akt-Dependent Manner1

Jackson, Jennifer B; Pallas, David C
Fonte: Neoplasia Press Inc. Publicador: Neoplasia Press Inc.
Tipo: Artigo de Revista Científica
Publicado em /07/2012 Português
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Heterotrimeric protein phosphatase 2A (PP2A) consists of catalytic C (PP2Ac), structural A, and regulatory B-type subunits, and its dysfunction has been linked to cancer. Reversible methylation of PP2Ac by leucine carboxyl methyltransferase 1 (LCMT-1) and protein phosphatase methylesterase 1 (PME-1) differentially regulates B-type subunit binding and thus PP2A function. Polyomavirus middle (PyMT) and small (PyST) tumor antigens and SV40 small tumor antigen (SVST) are oncoproteins that block PP2A function by replacing certain B-type subunits, resulting in cellular transformation. Whereas the B-type subunits replaced by these oncoproteins seem to exhibit a binding preference for methylated PP2Ac, PyMT does not. We hypothesize that circumventing the normal cellular control of PP2A by PP2Ac methylation is a general strategy for ST- and MT-mediated transformation. Two predictions of this hypothesis are (1) that PyST and SVST also bind PP2A in a methylation-insensitive manner and (2) that down-regulation of PP2Ac methylation will activate progrowth and prosurvival signaling and promote transformation. We found that SVST and PyST, like PyMT, indeed form PP2A heterotrimers independently of PP2Ac methylation. In addition, reducing PP2Ac methylation through LCMT-1 knockdown or PME-1 overexpression enhanced transformation by activating the Akt and p70/p85 S6 kinase (S6K) pathways...

‣ High-Resolution Mapping of a Fruit Firmness-Related Quantitative Trait Locus in Tomato Reveals Epistatic Interactions Associated with a Complex Combinatorial Locus1[W][OA]

Chapman, Natalie H.; Bonnet, Julien; Grivet, Laurent; Lynn, James; Graham, Neil; Smith, Rebecca; Sun, Guiping; Walley, Peter G.; Poole, Mervin; Causse, Mathilde; King, Graham J.; Baxter, Charles; Seymour, Graham B.
Fonte: American Society of Plant Biologists Publicador: American Society of Plant Biologists
Tipo: Artigo de Revista Científica
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Fruit firmness in tomato (Solanum lycopersicum) is determined by a number of factors including cell wall structure, turgor, and cuticle properties. Firmness is a complex polygenic trait involving the coregulation of many genes and has proved especially challenging to unravel. In this study, a quantitative trait locus (QTL) for fruit firmness was mapped to tomato chromosome 2 using the Zamir Solanum pennellii interspecific introgression lines (ILs) and fine-mapped in a population consisting of 7,500 F2 and F3 lines from IL 2-3 and IL 2-4. This firmness QTL contained five distinct subpeaks, Firs.p.QTL2.1 to Firs.p.QTL2.5, and an effect on a distal region of IL 2-4 that was nonoverlapping with IL 2-3. All these effects were located within an 8.6-Mb region. Using genetic markers, each subpeak within this combinatorial locus was mapped to a physical location within the genome, and an ethylene response factor (ERF) underlying Firs.p.QTL2.2 and a region containing three pectin methylesterase (PME) genes underlying Firs.p.QTL2.5 were nominated as QTL candidate genes. Statistical models used to explain the observed variability between lines indicated that these candidates and the nonoverlapping portion of IL 2-4 were sufficient to account for the majority of the fruit firmness effects. Quantitative reverse transcription-polymerase chain reaction was used to quantify the expression of each candidate gene. ERF showed increased expression associated with soft fruit texture in the mapping population. In contrast...

‣ ICSM: An order N method for calculating electrostatic interactions added to TINKER

Baker, Katherine; Baumketner, Andrij; Lin, Yuchun; Deng, Shaozhong; Jacobs, Donald; Cai, Wei
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
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We present an order N method for calculating electrostatic interactions that has been integrated into the molecular dynamics portion of the TINKER Molecular Modeling package. This method, introduced in a previous paper [J. Chem. Phys. 131 (2009) 154103] and termed the Image-Charge Solvation Model (ICSM), is a hybrid electrostatic approach that combines the strengths of both explicit and implicit representations of the solvent. A multiple-image method is used to calculate reaction fields due to the implicit part while the Fast Multipole Method (FMM) is used to calculate the Coulomb interactions for all charges, including the explicit part. The integrated package is validated through test simulations of liquid water. The results are compared with those obtained by the Particle Mesh Ewald (PME) method that is built in the TINKER package. Timing performance of TINKER with the integrated ICSM is benchmarked on bulk water as a function of the size of the system. In particular, timing analysis results show that the ICSM outperforms the PME for sufficiently large systems with the break-even point at around 30,000 particles in the simulated system.

‣ The effect of antifungal hot-water treatments on papaya postharvest quality and activity of pectinmethylesterase and polygalacturonase

Chávez-Sánchez, Ignacio; Carrillo-López, Armando; Vega-García, Misael; Yahia, Elhadi M.
Fonte: Springer-Verlag Publicador: Springer-Verlag
Tipo: Artigo de Revista Científica
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The effect of antifungal hot-water treatments (AHWT) at 55 °C for 0, 3, 6 and 9 min on quality attributes and cell-wall enzymatic activity during storage at 25 °C was investigated in papaya fruit. The total soluble solids (TSS), pH, titratable acidity (TA), firmness and fresh weight loss were not affected, whereas color on skin was negatively affected by the treatments of 6- and 9-min. However, the skin color was not different between the 3-min treated fruit and the untreated fruit during the storage. Decay was delayed and reduced by AHWT. We observed that the 3-min treatment of 55 °C did not affect softening and quality of papaya cv Maradol when applied as a pesticide-free treatment at color-break stage of papaya. PME (Pectinmethylesterase) and PG (Polygalacturonase) activities were not significantly affected by AHWT. We concluded that the AHWT did not affect the softening process from papaya pulp since the cell-wall enzyme activity (PME and PG) was not altered by treatments.

‣ Compression Garments and Recovery from Eccentric Exercise: A 31P-MRS Study

Trenell, Michael I.; Rooney, Kieron B.; Sue, Carolyn M.; Thomspon, Campbell H.
Fonte: Asist Group Publicador: Asist Group
Tipo: Artigo de Revista Científica
Publicado em 01/03/2006 Português
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The low oxidative demand and muscular adaptations accompanying eccentric exercise hold benefits for both healthy and clinical populations. Compression garments have been suggested to reduce muscle damage and maintain muscle function. This study investigated whether compression garments could benefit metabolic recovery from eccentric exercise. Following 30-min of downhill walking participants wore compression garments on one leg (COMP), the other leg was used as an internal, untreated control (CONT). The muscle metabolites phosphomonoester (PME), phosphodiester (PDE), phosphocreatine (PCr), inorganic phosphate (Pi) and adenosine triphosphate (ATP) were evaluated at baseline, 1-h and 48-h after eccentric exercise using 31P-magnetic resonance spectroscopy. Subjective reports of muscle soreness were recorded at all time points. The pressure of the garment against the thigh was assessed at 1-h and 48-h following exercise. There was a significant increase in perceived muscle soreness from baseline in both the control (CONT) and compression (COMP) leg at 1-h and 48-h following eccentric exercise (p < 0.05). Relative to baseline, both CONT and COMP showed reduced pH at 1-h (p < 0.05). There was no difference between CONT and COMP pH at 1-h. COMP legs exhibited significantly (p < 0.05) elevated skeletal muscle PDE 1-h following exercise. There was no significant change in PCr/Pi...

‣ Peak Detection Method Evaluation for Ion Mobility Spectrometry by Using Machine Learning Approaches

Hauschild, Anne-Christin; Kopczynski, Dominik; D’Addario, Marianna; Baumbach, Jörg Ingo; Rahmann, Sven; Baumbach, Jan
Fonte: MDPI Publicador: MDPI
Tipo: Artigo de Revista Científica
Publicado em 16/04/2013 Português
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Ion mobility spectrometry with pre-separation by multi-capillary columns (MCC/IMS) has become an established inexpensive, non-invasive bioanalytics technology for detecting volatile organic compounds (VOCs) with various metabolomics applications in medical research. To pave the way for this technology towards daily usage in medical practice, different steps still have to be taken. With respect to modern biomarker research, one of the most important tasks is the automatic classification of patient-specific data sets into different groups, healthy or not, for instance. Although sophisticated machine learning methods exist, an inevitable preprocessing step is reliable and robust peak detection without manual intervention. In this work we evaluate four state-of-the-art approaches for automated IMS-based peak detection: local maxima search, watershed transformation with IPHEx, region-merging with VisualNow, and peak model estimation (PME). We manually generated a gold standard with the aid of a domain expert (manual) and compare the performance of the four peak calling methods with respect to two distinct criteria. We first utilize established machine learning methods and systematically study their classification performance based on the four peak detectors’ results. Second...

‣ Regulation of PP2AC Carboxylmethylation and Cellular Localisation by Inhibitory Class G-Protein Coupled Receptors in Cardiomyocytes

Longman, Michael R.; Ranieri, Antonella; Avkiran, Metin; Snabaitis, Andrew K.
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 27/01/2014 Português
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The enzymatic activity of the type 2A protein phosphatase (PP2A) holoenzyme, a major serine/threonine phosphatase in the heart, is conferred by its catalytic subunit (PP2AC). PP2AC activity and subcellular localisation can be regulated by reversible carboxylmethylation of its C-terminal leucine309 (leu309) residue. Previous studies have shown that the stimulation of adenosine type 1 receptors (A1.Rs) induces PP2AC carboxylmethylation and altered subcellular distribution in adult rat ventricular myocytes (ARVM). In the current study, we show that the enzymatic components that regulate the carboxylmethylation status of PP2AC, leucine carboxylmethyltransferase-1 (LCMT-1) and phosphatase methylesterase-1 (PME-1) are abundantly expressed in, and almost entirely localised in the cytoplasm of ARVM. The stimulation of Gi-coupled A1.Rs with N6-cyclopentyladenosine (CPA), and of other Gi-coupled receptors such as muscarinic M2 receptors (stimulated with carbachol) and angiotensin II AT2 receptors (stimulated with CGP42112) in ARVM, induced PP2AC carboxylmethylation at leu309 in a concentration-dependent manner. Exposure of ARVM to 10 µM CPA increased the cellular association between PP2AC and its methyltransferase LCMT-1, but not its esterase PME-1. Stimulation of A1.Rs with 10 µM CPA increased the phosphorylation of protein kinase B at ser473...

‣ Taking into Account the Ion-induced Dipole Interaction in the Nonbonded Model of Ions

Li, Pengfei; Merz, Kenneth M.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
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Metal ions exist in almost half of the proteins in the protein databank and they serve as structural, electron-transfer and catalytic elements in the metabolic processes of organisms. Molecular Dynamics (MD) simulation is a powerful tool that provides information about biomolecular systems at the atomic level. Coupled with the growth in computing power, algorithms like the Particle Mesh Ewald (PME) method have become the accepted standard when dealing with long-range interactions in MD simulations. The nonbonded model of metal ions consists of an electrostatic plus 12-6 Lennard Jones (LJ) potential and is used largely because of its speed relative to more accurate models. In previous work we found that ideal parameters do not exist that reproduce several experimental properties for M(II) ions simultaneously using the nonbonded model coupled with the PME method due to the underestimation of metal ion-ligand interactions. Via a consideration of the nature of the nonbonded model, we proposed that the observed error largely arises from overlooking charge-induced dipole interactions. The electrostatic plus 12-6 LJ potential model works reasonably well for neutral systems but does struggle with more highly charged systems. In the present work we designed and parameterized a new nonbonded model for metal ions by adding a 1/r4 term to the 12-6 model. We call it the 12-6-4 LJ-type nonbonded model due to its mathematical construction. Parameters were determined for 16 +2 metal ions for the TIP3P...