Food Interactions, Sirtuins, Genes, Homeostasis, and General Discussion
Chuong Pham-Huy, Bruno Pham Huy in Food and Lifestyle in Health and Disease, 2022
The key difference between RNA and DNA structures is that the ribose sugar in RNA has a hydroxyl (-OH) group which is absent in DNA, and the thymine base of DNA is replaced by the uracil base in RNA (107, 111–113). The nucleotides that comprise DNA include adenine (A), guanine (G), cytosine (C), and thymine (T); whereas RNA nucleotides include A, G, C, and uracil (U). Moreover, RNA has only one long strand or chain in almost species, except in some viruses, while DNA has a double strand and looks like a twisted ladder in all species from bacteria and plants to invertebrates and humans (107, 111–113). DNA is defined as a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms. The main role of RNA is to transfer the genetic code needed for the creation of proteins from the nucleus to the ribosome (111). This process prevents the DNA from having to leave the nucleus. This keeps the DNA and genetic code protected from damage. Without RNA, proteins could never be made. RNA molecules are not only involved in protein synthesis, but also sometimes in the transmission of genetic information (111).
Introduction to Cancer
David E. Thurston, Ilona Pysz in Chemistry and Pharmacology of Anticancer Drugs, 2021
The UV band, which is invisible to the human eye, constitutes one component of the spectrum of sunlight and represents approximately 3% of all the solar radiation reaching the Earth’s surface. Three types of UV light have been identified. One of these, UV-C (200 to 290 nm), is generally thought to be the most carcinogenic. UV-B (290 to 320 nm) causes the most sunburn, and UV-A (320 to 400 nm), which can be up to 1,000 times stronger than UV-B, is able to penetrate underlying tissues of the skin leading to “photo-aging” damage. For many years it was thought that UV-A could not cause any lasting damage. However, more recent studies strongly suggest that it may also enhance the development of skin cancers. Fortunately, the ozone layer absorbs most of the more carcinogenic UV-C radiation, although there is presently concern that depletion of the ozone layer through the release of chlorofluorocarbons used in the air conditioner and refrigeration industries and in the production of Styrofoam insulation may increase the intensity of UV-C at the Earth’s surface in the future. UV radiation occurs at a similar wavelength to the region of maximum absorbance by DNA (i.e., 260 nm), and the major damage is intrastrand covalent linkage of adjacent pyrimidines (usually thymines) to form so-called thymine dimers. These thymine dimers create distortions in the DNA helix and can block replication and transcription, thus leading to tumorigenesis.
Drug Analysis of Protein Microspheres: From Pharmaceutical Preparation to In Vivo Fate
Neville Willmott, John Daly in Microspheres and Regional Cancer Therapy, 2020
FUra belongs to the antimetabolite class of antitumor drugs, and although various mechanisms of action have been defined, it is still uncertain which is the most significant.68 FUra has been shown to inhibit thymidylate synthetase after being first converted to 5-fluoro-2′-deoxyuridine monophosphate via a series of enzymic steps and then forming a ternary complex with N5, N10-methylene tetra-hydrofolate and thymidylate synthetase, thus inhibiting the conversion of uracil into thymine.76,77 The incorporation of thymine into DNA forms an essential step in DNA synthesis. This effect may be modulated by intracellular pools of nucleosides. As well as inhibiting DNA synthesis, it is possible that an appropriate metabolite of FUra, such as 2′-dFUrd triphosphate, might become incorporated into DNA: the significance of this in terms of cytotoxicity is not known.78,79 FUra is incorporated into all species of RNA with the greatest effects being on mRNA and rRNA, and in some cell lines there is a link between incorporation into RNA and cytotoxicity.80–82
Consequences and repair of radiation-induced DNA damage: fifty years of fun questions and answers
Published in International Journal of Radiation Biology, 2022
Initially we wanted to know how individual radiolysis products interacted with DNA polymerases? Did they block the polymerase and were thus potentially lethal, did they miscode and were thus potentially mutagenic or were they readily bypassed, code correctly and were thus innocuous? To answer some of these questions, my first chemist post-doc, Hiroshi Ide from Japan, introduced thymine glycols (Tg) into single stranded M13 DNA by osmium tetroxide treatment (Beer et al. 1966; Frenkel et al. 1981), and urea residues by alkaline treatment of the thymine glycol lesions (Ide et al. 1985; Kow and Wallace 1985). Using sequencing gel analysis, we found both lesions to be blocks to both E. coli DNA polymerase I (Pol I) and T4 DNA polymerase (Ide et al. 1985). Interestingly, DNA synthesis was terminated opposite Tg, the base inserted was later shown to be the correctly paired A (Clark and Beardsley 1987), but one base prior to urea, similar to what had been observed with abasic sites (Strauss et al. 1982; Sagher and Strauss 1983, 1985). We always tried to relate the structures of the individual lesions to their in vitro interactions with DNA polymerases and other enzymes. For example, the base pairing face of thymine glycol was intact (instructive) while urea (non-instructive) was a much smaller breakdown product of thymine. This type of in vitro information was then extremely helpful to our predicting their biological consequences.
Dosimetry study on Auger electron-emitting nuclear medicine radioisotopes in micrometer and nanometer scales using Geant4-DNA simulation
Published in International Journal of Radiation Biology, 2020
Seifi Moradi Mahdi, Shirani Bidabadi Babak
The geometric model of the DNA molecule considered by Raisali et al. (2013) consists of 41 base pair (82 nucleotides), with atom 123I was located at the base position of thymine in the 21st base pair. This position is related to the location of the IdUrd. As shown in Figure 1, each sugar-phosphate group is simulated in volumes, a height of 0.33 nm, an inner radius of 0.5 nm and an outer radius of 1.185 nm. Each nucleotide contains a sugar-phosphate group and its related base, in such way that the volume of each sugar-phosphate group is 0.24 nm3. This volume is the total volume of the atoms of a sugar-phosphate group. All volumes are filled with liquid water. Considering that the spiral of the DNA molecule spins 360° after 10 nucleotide pairs, an angle of 36° is intended to simulate the rotational angle for each nucleotide.
DNA damage analysis concerning GSTM1 and GSTT1 gene polymorphism in gold jewellery workers from Peshawar Pakistan
Published in Biomarkers, 2020
Muhammad Khisroon, Ajmal Khan, Asma Ayub, Ihsan Ullah, Javeed Farooqi, Abid Ullah
In Pakistan, no mega-scale gold mining is done due to scarcity of natural gold deposits and indigenous gold production is done by artisan and small-scale gold mining (ASGM) and gold jewellery workers (Gosselin and Dubé 2005). For the extraction of gold, jewellery workers use aqua regia and in this process, nitric oxide is released (Jayakumar and Sasikala 2008, Telmer and Veiga 2009). Nitric oxide (NO) is produced during the extraction of gold by gold jewellery workers (Arun et al. 2016). The NO produces reactive species of nitrogen and oxygen (RNS and ROS) so cause DNA damage, lipid peroxidation, and protein oxidation (Aitken and Curry 2011, Aitken et al. 2012, Arun et al. 2016). The NO deaminates cytosine to uracil and 5-methylcytosine to thymine hence causes mutagenicity in the cells (Nguyen et al. 1992). The ROS and RNS cause mutagenicity by microcystin-LR (Wang et al. 2015). Gold jewellery workers are also exposed to hazardous substances such as heavy metals (lead, silver, cadmium, mercury, antimony, beryllium, zinc, aluminium, zinc, copper, and arsenic), inorganic chemicals (trichloroethylene, aluminium oxide, asbestos, and silica), organic substances and solvents (xylene and toluene) (Speelman et al. 2004, Lansdown 2014, Abo-Zeid et al. 2015). These heavy metals and other organic and inorganic substances also cause DNA damage (Serment-Guerrero et al. 2011, Aktepe et al. 2015).