Oxidative stress and pre-eclampsia
Pankaj Desai in Pre-eclampsia, 2020
To understand free radicals easily, we will visit the atomic model that was taught to us in schools. Each atom is made of extremely tiny particles called “protons”, “neutrons” and “electrons”. Protons and neutrons are in the centre of the atom, making up the nucleus. Electrons surround the nucleus (Figure 4.1). Protons have a positive charge. Electrons have a negative charge. The charge on the proton and electron are the same size but opposite. Neutrons have no charge. Because opposite charges attract, protons and electrons attract each other. Many new subatomic particles have since been added. The neutrinos and the bosons are some of them. However, for our understanding, the role of free radicals in health and diseases, the simplest model of electrons, protons and neutrons will suffice.
Fundamental Concepts and Quantities
Shaheen A. Dewji, Nolan E. Hertel in Advanced Radiation Protection Dosimetry, 2019
The nucleus of an atom is composed of protons and neutrons. Protons are formed by the combination of two up quarks and one down quark, with each up quark having a unit charge of +2/3 and the down quark having a unit charge, yielding a net unit charge for the proton of +1 (1 unit charge = Coulombs). The proton has a rest mass of kg (Baum, Knox, and Miller 2002) or, using the mass-energy relationship , 938.272 where one atomic mass unit (AMU) is taken to be 931.5 . The number of protons in an atom determines its atomic number (Z) and, therefore, the chemical properties of charge-neutral elements.
Imaging and Principles of Uro-Radiology
Manit Arya, Taimur T. Shah, Jas S. Kalsi, Herman S. Fernando, Iqbal S. Shergill, Asif Muneer, Hashim U. Ahmed in MCQs for the FRCS(Urol) and Postgraduate Urology Examinations, 2020
Which of the following statements is INCORRECT?T1-weighted MRI images show water to be dark.T2-weighted MRI images show water to be bright.Gadolinium uptake in tissues makes them appear brighter on T1-weighted MRI images.Neutrons in the nucleus of the hydrogen atom have a negative charge.Gadolinium should not be given if eGFR is less than 30 mL/min/1.73 m2 due to risk of nephrogenic systemic fibrosis.
New cyclopentaquinoline and 3,5-dichlorobenzoic acid hybrids with neuroprotection against oxidative stress for the treatment of Alzheimer’s disease
Published in Journal of Enzyme Inhibition and Medicinal Chemistry, 2023
Kamila Czarnecka, Małgorzata Girek, Paweł Kręcisz, Robert Skibiński, Kamil Łątka, Jakub Jończyk, Marek Bajda, Piotr Szymczyk, Grzegorz Galita, Jacek Kabziński, Ireneusz Majsterek, Alba Espargaró, Raimon Sabate, Paweł Szymański
Corina online (Molecular Networks and Altamira) was used to create three-dimensional structures of compounds, that were then prepared using Sybyl 8.0 (Tripos). Protonation states were inspected, hydrogen atoms were added, atom types were checked and Gesteiger-Marsili charges were assigned. All ligands were docked to acetylcholinesterase from 2CKM and to butyrylcholinesterase based on a 1P0I crystal structure using GoldSuite 5.1 (CCDC). Before docking, the proteins were prepared in the following way: all histidine residues were protonated at Nε, the hydrogen atoms were added, ligand and water molecules were removed; the binding site was defined as all amino acid residues within 10 Å from bis-(7)-tacrine for AChE, and 20 Å from the glycerol molecule for BuChE. A standard set of genetic algorithms with a population size of 100, number of operations 100 000, and clustering with a tolerance of 1 Å was applied. After docking process, 10 ligand poses, sorted by GoldScore (for AChE) and ChemScore (for BuChE) were obtained. The results were visualised by PyMOL 0.99rc6 (DeLano Scientific LLC).
An approach to assessing the contribution of the high LET effect in strategies for Auger endoradiotherapy
Published in International Journal of Radiation Biology, 2023
Pavel Lobachevsky, Colin Skene, Laura Munforte, Andrea Smith, Jonathan White, Roger F. Martin
A quite different highly damaging component of Auger decay is described as molecular fragmentation. Multiple electrons originate from the decaying atom, resulting in a build-up of a positive charge on the daughter atom. The build-up and dissipation of the charge is a dynamic event, and in the case of decay of 125I, the maximum transient charge is about +6 (Kummerle and Pomplun 2012). This is the setting for what has been called a ‘Coulombic explosion’ – repulsion of like charges according to Coulomb’s Law, resulting in molecular fragmentation (Pomplun and Sutmann 2004). The relative contribution of molecular fragmentation versus electron irradiation has been the subject of discussion for decades (Hofer et al. 1978), and they seem to be similar (Lobachevsky and Martin 2000). Although chemical details are uncertain, DNA strand breaks are induced in the vicinity of the decaying atom, and there is a consensus that for DNA labeled by incorporation of 125I-iododeoxyuridine, there is an approximately 1:1 relationship between 125I decays in DNA and decay-induced DNA double-strand breaks (DSBs) (Martin and Feinendegen 2016).
Advancements in the use of Auger electrons in science and medicine during the period 2015–2019
Published in International Journal of Radiation Biology, 2023
The removal of an inner shell electron from an atom leaves the atom in an excited state. Atomic relaxation to the ground state occurs via radiative and nonradiative processes within the atom containing the original vacancy, and via processes that take place in neighboring atoms. Radiative processes are those that emit photons such as characteristic X-rays. Nonradiative processes emit Auger electrons, Coster-Kronig (CK) electrons, and super-CK electrons. These categories of electrons, often collectively referred to simply as Auger electrons, are characterized by the shells and subshells involved with the transition. Radiative processes dominate K-shell transitions, whereas nonradiative processes dominate when the vacancy is in the L-shell and above. Nevertheless, the vacancy is filled rapidly which leads to the creation of new vacancies in higher subshells forming a cascade of atomic transitions that emit a shower of low energy Auger electrons and characteristic X-rays.
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