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
Friday, June 5, 2026
Tamsulosin (Flomax) - Prostate Health - Patient guide - What to expect
Using flomax tamsulosin safely usually depends on clear expectations, steady follow up, and realistic daily routines. It is commonly used for patients trying to improve urine flow from prostate enlargement. Main goal is not fast drama, but reliable improvement over time. Some patients notice benefit quickly, while others need dose adjustment, patience, or related lifestyle changes before progress becomes obvious. Patients who want basic orientation can review https://lucasclinic.com/prostate-health/flomax-tamsulosin/. Material like that is useful because it frames medicine inside real care decisions: when to take it, what changes deserve attention, and why follow up often matters more than casual online advice. Most medication trouble starts with ordinary disruption. Travel, illness, poor sleep, new over the counter products, or inconsistent timing can all affect results. Keeping routine stable gives clinicians cleaner picture when they decide whether treatment is helping. Patients should also remember that treatment sits inside prostate care, not in isolation. Sleep, diet, hydration, activity, and underlying conditions can shape how well plan works. That is why follow up visits should review whole pattern rather than one symptom in a vacuum. Follow through after prescription also matters. Refills should be planned before bottles run low, symptom notes should be brought to visits, and any major change in routine should be mentioned early. Many medication problems are easier to fix when clinician hears about them after first week of trouble rather than after several months of guessing. Safety planning should stay simple and direct. Patients should report fainting, severe dizziness, or urinary symptoms that keep worsening rather than assuming body will sort everything out. Fast communication often prevents avoidable urgent visits. General guidance for this medication category is collected at https://lucasclinic.com/prostate-health/. That broader view can support better questions at next visit and more realistic expectations between visits. Patients rarely need perfect routine, but they do need honest reporting, steady habits, and enough follow up to catch problems before they grow.
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