246 research outputs found

    A Halomethane thermochemical network from iPEPICO experiments and quantum chemical calculations

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    Internal energy selected halomethane cations CH3Cl+, CH2Cl2+, CHCl3+, CH3F+, CH2F2+, CHClF2+ and CBrClF2+ were prepared by vacuum ultraviolet photoionization, and their lowest energy dissociation channel studied using imaging photoelectron photoion coincidence spectroscopy (iPEPICO). This channel involves hydrogen atom loss for CH3F+, CH2F2+ and CH3Cl+, chlorine atom loss for CH2Cl2+, CHCl3+ and CHClF2+, and bromine atom loss for CBrClF2+. Accurate 0 K appearance energies, in conjunction with ab initio isodesmic and halogen exchange reaction energies, establish a thermochemical network, which is optimized to update and confirm the enthalpies of formation of the sample molecules and their dissociative photoionization products. The ground electronic states of CHCl3+, CHClF2+ and CBrClF2+ do not confirm to the deep well assumption, and the experimental breakdown curve deviates from the deep well model at low energies. Breakdown curve analysis of such shallow well systems supplies a satisfactorily succinct route to the adiabatic ionization energy of the parent molecule, particularly if the threshold photoelectron spectrum is not resolved and a purely computational route is unfeasible. The ionization energies have been found to be 11.47 Β± 0.01 eV, 12.30 Β± 0.02 eV and 11.23 Β± 0.03 eV for CHCl3, CHClF2 and CBrClF2, respectively. The updated 0 K enthalpies of formation, βˆ†fHo0K(g) for the ions CH2F+, CHF2+, CHCl2+, CCl3+, CCl2F+ and CClF2+ have been derived to be 844.4 Β± 2.1, 601.6 Β± 2.7, 890.3 Β± 2.2, 849.8 Β± 3.2, 701.2 Β± 3.3 and 552.2 Β± 3.4 kJ mol–1, respectively. The βˆ†fHo0K(g) values for the neutrals CCl4, CBrClF2, CClF3, CCl2F2 and CCl3F and have been determined to be –94.0 Β± 3.2, –446.6 Β± 2.7, –702.1 Β± 3.5, –487.8 Β± 3.4 and –285.2 Β± 3.2 kJ mol–1, respectively

    Incidence, Outcomes, and Predictors of Ventricular Thrombus after Reperfused ST-Segment-Elevation Myocardial Infarction by Using Sequential Cardiac MR Imaging

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    [EN] Purpose: To characterize the incidence, outcomes, and predictors of left ventricular (LV) thrombus by using sequential cardiac magnetic resonance (MR) imaging after ST-segment-elevation myocardial infarction (STEMI). Materials and Methods: Written informed consent was obtained from all patients, and the study protocol was approved by the committee on human research. In a cohort of 772 patients with STEMI, 392 (mean age, 58 years; range, 24-89 years) were retrospectively selected who were studied with cardiac MR imaging at 1 week and 6 months. Cardiac MR imaging guided the initiation and withdrawal of anticoagulants. Patients with LV thrombus at 6 months were restudied at 1 year. For predicting the occurrence of LV thrombus, a multiple regression model was applied. Results: LV thrombus was detected in 27 of 392 patients (7%): 18 (5%) at 1 week and nine (2%) at 6 months. LV thrombus resolved in 22 of 25 patients (88%) restudied within the first year. During a mean follow-up of 181 weeks 6 168, patients with LV thrombus displayed a very low rate of stroke (0%), peripheral embolism (0%), and severe hemorrhage (n = 1, 3.7%). LV ejection fraction (LVEF) less than 50% (P < .001) and anterior infarction (P = .008) independently helped predict LV thrombus. The incidence of LV thrombus was as follows: (a) nonanterior infarction, LVEF 50% or greater (one of 135, 1%); (b) nonanterior infarction, LVEF less than 50% (one of 50, 2%); (c) anterior infarction, LVEF 50% or greater (two of 92, 2%); and (d) anterior infarction, LVEF less than 50% (23 of 115, 20%) (P < .001 for the trend). Conclusion: Cardiac MR imaging contributes information for the diagnosis and therapy of LV thrombus after STEMI. Patients with simultaneous anterior infarction and LVEF less than 50% are at highest risk. (C) RSNA, 2017Study supported by Instituto de Salud Carlos III and FEDER (CB16/11/00486, PI14/00271, PIE15/00013) and Generalitat Valenciana (PROMETEO/2013/007).Cambronero-Cortinas, E.; Bonanad, C.; Monmeneu, J.; LΓ³pez-Lereu, M.; Gavara-DoΓ±ate, J.; De Dios, E.; Rios, C.... (2017). Incidence, Outcomes, and Predictors of Ventricular Thrombus after Reperfused ST-Segment-Elevation Myocardial Infarction by Using Sequential Cardiac MR Imaging. Radiology. 284(2):372-380. https://doi.org/10.1148/radiol.2017161898S372380284

    The effect of adenosine monophosphate deaminase overexpression on the accumulation of umami-related metabolites in tomatoes

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    Taste is perceived as one of a combination of five sensations, sweet, sour, bitter, salty, and umami. The umami taste is best known as a savoury sensation and plays a central role in food flavour, palatability, and eating satisfaction. Umami flavour can be imparted by the presence of glutamate and is greatly enhanced by the addition of ribonucleotides, such as inosine monophosphate (IMP) and guanosine monophosphate (GMP). The production of IMP is regulated by the enzyme adenosine monophosphate (AMP) deaminase which functions to convert AMP into IMP. We have generated transgenic tomato (Solanum lycopersicum) lines over expressing AMP deaminase under the control of a fruit-specific promoter. The transgenic lines showed substantially enhanced levels of AMP deaminase expression in comparison to the wild-type control. Elevated AMP deaminase levels resulted in the reduced accumulation of glutamate and increased levels of the umami nucleotide GMP. AMP concentrations were unchanged. The effects on the levels of glutamate and GMP were unexpected and are discussed in relation to the metabolite flux within this pathway

    Increased Expression of the Auxiliary Ξ²(2)-subunit of Ventricular L-type Ca(2+) Channels Leads to Single-Channel Activity Characteristic of Heart Failure

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    BACKGROUND: Increased activity of single ventricular L-type Ca(2+)-channels (L-VDCC) is a hallmark in human heart failure. Recent findings suggest differential modulation by several auxiliary Ξ²-subunits as a possible explanation. METHODS AND RESULTS: By molecular and functional analyses of human and murine ventricles, we find that enhanced L-VDCC activity is accompanied by altered expression pattern of auxiliary L-VDCC Ξ²-subunit gene products. In HEK293-cells we show differential modulation of single L-VDCC activity by coexpression of several human cardiac Ξ²-subunits: Unlike Ξ²(1) or Ξ²(3) isoforms, Ξ²(2a) and Ξ²(2b) induce a high-activity channel behavior typical of failing myocytes. In accordance, Ξ²(2)-subunit mRNA and protein are up-regulated in failing human myocardium. In a model of heart failure we find that mice overexpressing the human cardiac Ca(V)1.2 also reveal increased single-channel activity and sarcolemmal Ξ²(2) expression when entering into the maladaptive stage of heart failure. Interestingly, these animals, when still young and non-failing (β€œAdaptive Phase”), reveal the opposite phenotype, viz : reduced single-channel activity accompanied by lowered Ξ²(2) expression. Additional evidence for the cause-effect relationship between Ξ²(2)-subunit expression and single L-VDCC activity is provided by newly engineered, double-transgenic mice bearing both constitutive Ca(V)1.2 and inducible Ξ²(2) cardiac overexpression. Here in non-failing hearts induction of Ξ²(2)-subunit overexpression mimicked the increase of single L-VDCC activity observed in murine and human chronic heart failure. CONCLUSIONS: Our study presents evidence of the pathobiochemical relevance of Ξ²(2)-subunits for the electrophysiological phenotype of cardiac L-VDCC and thus provides an explanation for the single L-VDCC gating observed in human and murine heart failure

    Effects of Dopamine on Sensitivity to Social Bias in Parkinson's Disease

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    Patients with Parkinson's disease (PD) sometimes develop impulsive compulsive behaviours (ICBs) due to their dopaminergic medication. We compared 26 impulsive and 27 non-impulsive patients with PD, both on and off medication, on a task that examined emotion bias in decision making. No group differences were detected, but patients on medication were less biased by emotions than patients off medication and the strongest effects were seen in patients with ICBs. PD patients with ICBs on medication also showed more learning from negative feedback and less from positive feedback, whereas off medication they showed the opposite effect

    RNA Methylation by the MIS Complex Regulates a Cell Fate Decision in Yeast

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    For the yeast Saccharomyces cerevisiae, nutrient limitation is a key developmental signal causing diploid cells to switch from yeast-form budding to either foraging pseudohyphal (PH) growth or meiosis and sporulation. Prolonged starvation leads to lineage restriction, such that cells exiting meiotic prophase are committed to complete sporulation even if nutrients are restored. Here, we have identified an earlier commitment point in the starvation program. After this point, cells, returned to nutrient-rich medium, entered a form of synchronous PH development that was morphologically and genetically indistinguishable from starvation-induced PH growth. We show that lineage restriction during this time was, in part, dependent on the mRNA methyltransferase activity of Ime4, which played separable roles in meiotic induction and suppression of the PH program. Normal levels of meiotic mRNA methylation required the catalytic domain of Ime4, as well as two meiotic proteins, Mum2 and Slz1, which interacted and co-immunoprecipitated with Ime4. This MIS complex (Mum2, Ime4, and Slz1) functioned in both starvation pathways. Together, our results support the notion that the yeast starvation response is an extended process that progressively restricts cell fate and reveal a broad role of post-transcriptional RNA methylation in these decisions

    Anion-Sensitive Regions of L-Type CaV1.2 Calcium Channels Expressed in HEK293 Cells

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    L-type calcium currents (ICa) are influenced by changes in extracellular chloride, but sites of anion effects have not been identified. Our experiments showed that CaV1.2 currents expressed in HEK293 cells are strongly inhibited by replacing extracellular chloride with gluconate or perchlorate. Variance-mean analysis of ICa and cell-attached patch single channel recordings indicate that gluconate-induced inhibition is due to intracellular anion effects on Ca2+ channel open probability, not conductance. Inhibition of CaV1.2 currents produced by replacing chloride with gluconate was reduced from ∼75%–80% to ∼50% by omitting Ξ² subunits but unaffected by omitting Ξ±2Ξ΄ subunits. Similarly, gluconate inhibition was reduced to ∼50% by deleting an Ξ±1 subunit N-terminal region of 15 residues critical for Ξ² subunit interactions regulating open probability. Omitting Ξ² subunits with this mutant Ξ±1 subunit did not further diminish inhibition. Gluconate inhibition was unchanged with expression of different Ξ² subunits. Truncating the C terminus at AA1665 reduced gluconate inhibition from ∼75%–80% to ∼50% whereas truncating it at AA1700 had no effect. Neutralizing arginines at AA1696 and 1697 by replacement with glutamines reduced gluconate inhibition to ∼60% indicating these residues are particularly important for anion effects. Expressing CaV1.2 channels that lacked both N and C termini reduced gluconate inhibition to ∼25% consistent with additive interactions between the two tail regions. Our results suggest that modest changes in intracellular anion concentration can produce significant effects on CaV1.2 currents mediated by changes in channel open probability involving Ξ² subunit interactions with the N terminus and a short C terminal region
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