Endogenous DNA damage in humans: a review of quantitative data
By academic.oup.com
DNA damage plays a major role in mutagenesis, carcinogenesis and ageing. The chemical events that lead to DNA damage include hydrolysis, exposure to reactive oxygen substances (ROS) and other reactive metabolites. These reactions are triggered by exposure to exogenous chemicals or they can result from metabolic, endogenous processes. The concentrations and mutagenic potentials of known carcinogens to which we are exposed in our environment are insufficient to explain the high incidence of sporadic cancer that is actually seen in our population (Epe, 2002). Innate factors can also not suffice to explain this high incidence. Epidemiology shows that, in developed societies, exogenous factors are a necessary condition in about 75–80% of cancer cases (Doll and Peto, 1981; Trichopoulos et al., 1994). So, mutations due to DNA damage, caused by unidentified exogenous agents, and to an increase in endogenous damage modulated by exogenous factors must play a role in most cases of cancer, in addition to changes in gene expression due to exogenous conditions. A thorough knowledge of the types and prevalence of endogenous DNA damage can be considered essential for an understanding of the interaction of exogenous agents and influences with endogenous processes in the induction of cancer and other diseases. In particular, this is important for risk analysis concerning low dose environmental factors. Endogenous DNA damage occurs at a high frequency compared with exogenous damage and the types of damage produced by normal cellular processes are identical or very similar to those caused by some environmental agents (Jackson and Loeb, 2001). The study of endogenous damage is also of importance to chemoprevention. It is evident that if an approach could be developed leading to a decrease in endogenous DNA damage and endogenous mutations, the incidence of cancer and other diseases might be substantially reduced, even without a reduction in exogenous mutations.
Oxidative DNA damage
In living cells ROS are formed continuously as a consequence of metabolic and other biochemical reactions as well as external factors. These ROS include superoxide (O2–·), hydrogen peroxide (H2O2), hydroxyl radicals (OH·) and singlet oxygen (1O2) and they can oxidize DNA, which can lead to several types of DNA damage, including oxidized bases and single‐ and double‐strand breaks. DNA damage produced by ROS is the most frequently occurring damage.
Oxidatively modified DNA is, despite extensive DNA repair, abundant in many human tissues, especially in tumours (Iida et al., 2001; Li et al., 2002). Many defence mechanisms within the organism have evolved to limit the levels of reactive oxidants and the damage they induce (Slupphaug et al., 2003). Oxidative stress occurs when the production of ROS exceeds the body’s natural antioxidant defence mechanisms, causing damage to macromolecules such as DNA, proteins and lipids. ROS also inactivate antioxidant enzymes (Kono and Fidovich, 1982; Tabatabaie and Floyd, 1994). So, as pointed out by Epe (2002), any change in the endogenous generation of ROS or cellular antioxidants or in the efficiency of DNA repair should cause a corresponding modulation of the steady‐state levels of oxidative DNA modifications, which in turn should modulate the mutation rate and ultimately the cancer incidence. Epidemiological evidence from different studies points to reduced risks for cancer, particularly in the upper gastrointestinal tract and airways, associated with a diet rich in antioxidants and/or a high content of antioxidants in plasma samples (Loft and Poulsen, 1996).
Data suggest that the rate of damage decreases with age, possibly along with the decreasing rate of metabolism, whereas the steady‐state levels increase due to failing repair (Loft and Poulsen, 1996).
Source: https://academic.oup.com/mutage/article/doi/10.1093/mutage/geh025/1482185/Endogenous-DNA-damage-in-humans-a-review-of
Saturday, June 13, 2026
Treating Tendonitis With Voltaren: Key Facts
When a person is diagnosed with tendonitis or seeks relief from it, selecting the most appropriate medication requires weighing multiple factors: the severity of symptoms, the patient's age and health history, and whether other medications are already being taken. A thoughtful treatment choice improves outcomes and reduces unnecessary side effects. Non-steroidal anti-inflammatory drugs, commonly called NSAIDs, represent one of the most widely used classes of pain-relief medications. They work by inhibiting cyclooxygenase enzymes, particularly COX-1 and COX-2, which are responsible for producing prostaglandins, the chemical mediators that sensitize pain receptors and drive inflammation. By reducing prostaglandin production, NSAIDs simultaneously relieve pain, reduce inflammation, and lower fever. They are effective for a wide range of painful conditions including musculoskeletal injuries, arthritis, menstrual pain, and dental pain. Among the medications available for pain relief medications, Voltaren provides a well-studied option that many patients discuss with their doctors. The clinical evidence supporting voltaren for tendonitis shows that it can be effective for managing this condition when used appropriately under medical supervision. Voltaren contains the active ingredient diclofenac, which works by acting on the biological pathways responsible for producing the symptoms associated with tendonitis. Understanding the mechanism helps patients appreciate why consistent use is often more effective than taking it only when symptoms become severe, as maintaining steady levels allows for more stable control. Patients managing tendonitis long-term should keep regular follow-up appointments to assess whether their treatment plan is still the best fit for their situation. As conditions change and new evidence emerges, treatment adjustments may be worthwhile. The https://mednewwsstoday.com/pain-relief/ resource section provides a helpful reference for staying current on medication options in this area.
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