China 
Africa 
Explore chapters and articles related to this topic
Microbial Control during Hydraulic Fracking Operations
Published in Kenneth Wunch, Marko Stipaničev, Max Frenzel, Microbial Bioinformatics in the Oil and Gas Industry, 2021
Renato De Paula, Irwan Yunus, Conor Pierce
An alternative to halogenated oxidizing biocides, and their associated risks, is hydrogen peroxide. Used throughout the oil and gas industry, hydrogen peroxide is an inorganic molecule available in a range of concentrations with long-term storage capability due to its relative stability when compared to the chlorine species discussed above. Prevailing theories regarding its mechanism of action state that hydrogen peroxide reacts with either a biological source of iron within the bacteria or iron/copper/manganese present in the treated fluid to generate a hydroxyl radical. This radical then causes cell death through the oxidation of DNA, proteins, and membrane lipids (Finnegan et al., 2010). More recent studies have proposed a DNA oxidation mechanism involving a ferryl radical formed from DNA-associated iron reacting with the peroxide, rather than from a hydroxyl radical. In either case, hydrogen peroxide can serve as an effective oxidizing biocide if the conditions to generate a reactive hydroxyl radical species are present (Linley et al., 2012).
1
Published in Debasis Bagchi, Manashi Bagchi, Metal Toxicology Handbook, 2020
Amit Madeshiya, Pradipta Banerjee, Suman Santra, Nandini Ghosh, Sayantani Karmakar, Debasis Bagchi, Sashwati Roy, Amitava Das
High concentration of iron in the body gives rise to free radicals that overpower the cellular antioxidant defense mechanisms, degrade biomolecules, and dysregulate cell signaling pathways [9]. Copper has the potential to induce oxidative stress either by catalyzing ROS formation through a Fenton-like reaction or by significantly decreasing the glutathione levels [10]. Chromium is considered as an occupational carcinogen that not only targets the lungs but also leads to adverse health conditions including gastrointestinal symptoms, hypotension, hepatic and renal failures, and sometimes stomach tumors [11]. The trivalent forms of the metalloid arsenic (As3+) are the most toxic and react with the thiol groups of proteins leading to neurological disorders [12]. Hallmarks of chronic exposure to arsenic include skin lesions, peripheral neuropathy, and anemia. Zinc deficiency is associated with poor diet and related to increased oxidative damage that results in increased lipid, protein, and DNA oxidation [13]. Cadmium enters the human body through the lungs and skin, and accumulates in the intestine and kidneys [14]. Cadmium-induced testicular damage and necrosis have been well documented. Lead damages cellular components via increased oxidative stress through direct ROS generation and via depletion of the cellular antioxidant pool [10]. Roles of some important metals and metalloids in redox biology and their implications in physiology and pathological states will be discussed in this chapter.
Cellular and Molecular Toxicology of Nanoparticles
Published in Vladimir Torchilin, Handbook of Materials for Nanomedicine, 2020
A. Zielińska, D. Santos, J. R. Campos, A. Santini, P. Severino, A. A. M. Shimojo, S. B. Souto, E. B. Souto
The genotoxicity can be evaluated by several methods including the following: (i) The evaluation of the oxidation of the DNA can occur directly by the determination of the presence of oxidized bases. The oxidized guanine 8-OHdG is a biomarker to DNA oxidation and can be measured by immunohistochemistry or high-performance liquid chromatography [30, 79]; (ii) single-cell gel electrophoresis (SCGE), also known as COMET assay, is a versatile, accurate yet simple and useful technique commonly used to measure DNA damage and repair in individual cells [61]. The COMET assay consists of electrophoresis, single-cell gel electrophoresis, which allows verifying the rupture in the DNA. The principal measurement of COMET is based on the migration of different DNA fragments in gel according to the length. The damage of the DNA fragments of DNA creates a “comet” tail, which is visualized after electrophoresis with the use of fluorescent dyes [22]. A drawback of this assay is a limitation in the detection of a very small and mitochondrial DNA [58, 79]; (iii) AMES test determines genetic mutations using several strains of Salmonella typhimurium and Escherichia coli [33, 52].
Urinary concentrations of amphenicol antibiotics in relation to biomarkers of oxidative DNA and RNA damage in school children
Published in Journal of Environmental Science and Health, Part A, 2022
Yang Geng, Man Hu, Yuan Yao, Ming Zhan, Ying Zhou
Our findings indicated that urinary TAP levels were significantly associated with urinary 8-OHdG, a biomarker for DNA oxidation. Meanwhile, a similar trend was also observed for CAP. The underlying mechanisms of TAP and CAP induced oxidative stress could be explained by previous in vitro and in vivo studies. Animal studies[17,28] revealed that low concentrations of individual and mixtures of CAP, TAP and FF significantly increased the malondialdehyde (MDA) levels of Daphnia magna which could lead to cellular oxidative damage in the organisms. Moreover, in vitro studies demonstrated that CAP stimulated oxidative stress in human neutrophils with a corresponding increase in ROS production[23] and CAP metabolites caused DNA damage in calf thymus mediated by the formation of 8-OHdG.[22]
Role of Ozone in Post-Harvest Disinfection and Processing of Horticultural Crops: A Review
Published in Ozone: Science & Engineering, 2022
S Vijay Rakesh Reddy, D.V Sudhakar Rao, R.R. Sharma, P. Preethi, R Pandiselvam
The complex process of microbial inactivation by ozone involves its action on various cell membranes and their constituents (fatty acids) along with cell components (enzymes and nucleic acids). Bacteria are single-celled microbes with a strong cell membrane. Ozone acts on these microscopic organisms by hampering their cellular metabolism through inhibition/blockage of enzyme systems. Adequate quantities of ozone break through their cell membrane, resulting in their inactivation/destruction. The mechanism by which ozone annihilates the target microbes could be explained in two ways: (i) the proteins, peptides, and other amino acids of vital enzymes are broken into smaller peptides through the oxidation process and (ii) the polyunsaturated fatty acids are oxidized to acid peroxidases (Chen et al. 2007). Harmful microbes are deactivated by disruption of plasma membranes or by the process of cell disintegration (Figure 1). Ozone was also shown to effectively deactivate the bacterial spores, viz., Bacillus sp. Transmission Electron Microscopy (TEM) studies indicated that ozone acts on the outer component of the bacterial spores, which constitutes 50% of spore volume and ultimately results in exposing the sensitive cortex and core components to ozone (Khadre, Yousef, and Kim 2001). Young and Setlow (2004) hypothesized that ozone acts by destroying the germinability of the microbial spores rather than directly killing through DNA oxidation/mutation. Researchers have further proved the damage caused to inner components of spores (cortex and core) by rupture that negatively influenced the germination.
Synthesis, crystal structure determination, DFT calculation, and Hirshfeld surface analysis of a new Zn(II) complex with the guaninium ligand
Published in Journal of Coordination Chemistry, 2020
Klai Kacim, Christian Jelsch, Christine Lucas, Frédéric Lefebvre, Werner Kaminsky, Cherif Ben Nasr, Kamel Kaabi
Over the past decades, there has been a sizable research effort on rational design and elaboration of transition metal complexes due to their interesting structural, chemical, and physical properties such as storage of gas, separation of molecules, catalyzing the chemicals, and delivery of drugs [1–5]. The interaction between divalent metal cations and nucleic acids has also been widely studied due to their importance for DNA-replication, transcription, and metabolic processes [6–11]. It is well known that metal atoms that interact with nucleobases in DNA and RNA can modify hydrogen bonds and cause DNA oxidation, thereby affecting the formation of the double helix and causing mutation points [12, 13]. Metal ions can bind directly to nucleic acid bases via the oxygen or nitrogen atoms of the bases. Guanine is one of the purine bases that take place into the composition of nucleic acids (DNA or RNA) and carry their genetic information. In this context, the molecular architecture of transition-metal complexes containing nucleobases is very useful, giving various molecular geometric shapes and high-dimensional architectures [14]. The chemistry of zinc compounds is gaining great attention due to their interesting structural features, catechol oxidase, schizonticidal, antimalarial, antimicrobial, tumor photosensitizers, and their potential use as agricultural biocides [15–18]. When considering biologically relevant transition metals, zinc is the second most abundant element found within cells, behind iron. Zinc ions (Zn2+) are known to facilitate diverse protein functions that are essential for life [19].