Mateus A. Gonçalves

Optimal wavelet signal compression as an efficient alternative to investigate molecular dynamics simulations: application to thermal and solvent effects of MRI probes

Currently, cancer is one of the most serious problems facing humanity, and one of the most widely used and versatile diagnostic techniques is magnetic resonance imaging (MRI), which may require an injection of contrast agents (CAs). CAs are paramagnetic compounds capable of increasing the relaxation rate of water protons, thereby obtaining clearer MRI examination images. In this work, the solvent and thermal effects on spectroscopic parameters of [Fe(H2O)6]2+, [Mn(H2O)6]2+, [Gd(H2O)8]3+, and γ-Fe2O3, coordinated to explicit water molecules, were studied in light of the classical and quantum methods. For the classical part of the simulation, a new method of selection of configurations from the molecular dynamics simulations, denominated optimal wavelet signal compression algorithm (OWSCA), is presented. Our findings indicate that OWSCA leads to a good agreement with the experimental available data and the thermal effects greatly influence our system. Thus, the molecular dynamics calculations are important for this type of system. Our results show the γ-Fe2O3 as a promising alternative to conventional contrast agents.

Molecular Modeling Studies of Piperidine Derivatives as New Acetylcholinesterase Inhibitors against Neurodegenerative Diseases

Neurodegenerative disorders are related to the progressive loss of structure or function and, eventually, death of neurons. These processes are responsible for diseases like Parkinson’s, Alzheimer’s, and Huntington’s, and the main molecular target for the drug design against these illnesses today is the enzyme acetylcholinesterase (AChE). Following this line, in the present work, we applied docking techniques to study some piperidine derivative inhibitors of AChE and further propose structures of six new AChE inhibitors as potential new drugs against neurodegenerative disorders. The best inhibitor proposed was submitted to additional molecular dynamics simulations steps.

Exploring EPR Parameters of 99Tc Complexes for Designing New MRI Probes: Coordination Environment, Solvent, and Thermal Effects on the Spectroscopic Properties

We have evaluated the solvent and thermal effects on spectroscopic parameters of 99Tc complexes coordinated to explicit water molecules. Molecular dynamics simulations were performed followed by hyperfine coupling constant calculations (). Our results show a significant increase of , which demonstrates that the studied compounds can be promising contrast agents in MRI.

Agentes de Contraste para Imagem por Ressonância Magnética: Uma Revisão

The Magnetic Resonance Imaging (MRI) is a noninvasive technique based on the magnetic properties of the H atoms. Currently, about 30% of MRI exams use paramagnetic compounds, which are defined as contrast agents (CAs), able to reduce the relaxation times (T1 and T2) of hydrogen atoms from water molecules. In this review, we show the main compounds employed as CAs. Among these, Gd complexes are frequently used, but problems related to their high toxicity and relaxivities, promoting the development of new ACs, such as iron oxides, hybrid compounds as well as Mn and Ni complexes, which are less toxic and more

Use of Ethylenediaminetetraacetic Acid as a Scavenger for Chromium from “Wet Blue” Leather Waste: Thermodynamic and Kinetics Parameters

One serious consequence of the current consumer society is the transformation of the environment into a waste receptacle arising from human activities. Because of the potential toxic effects of chromium solid waste containing this metal there are grounds for serious concern for the tanning and leather processing industry. The application of tannery waste as organic fertilizer has led to extensive contamination by chromium in agricultural areas and may cause the accumulation of this metal in soils and plants. This work evaluated the extraction of Cr