Leisure-time physical activity and DNA damage among Japanese workers

Genotoxicity Associated with 131I and 99mTc Exposure in Nuclear Medicine Staff: A Physical and Biological Monitoring Study

Nuclear medicine staff are constantly exposed to low doses of ionizing radiation. This study investigated the level of genotoxic effects in hospital employees exposed to routinely used ¹³¹I and ^99mTc in comparison with a control group. The study compared the results of physical and biological monitoring in peripheral blood lymphocytes. The effects of confounding factors, such as smoking status and physical activity, were also considered. Physical dosimetry monitoring revealed differences in the individual annual effective dose as measured by finger ring dosimeter and whole-body dosimeter between the ¹³¹I- and ^99mTc-exposed groups. The DNA damage studies revealed differences between the groups in terms of excess premature chromosome condensation (PCC) fragments and tail DNA. Physical activity and smoking status differentiated the investigated groups. When assessed by the level of physical activity, the highest mean values of tail DNA were observed for the ^99mTc group. When assessed by work-related physical effort, excess PCC fragments were significantly higher in the ¹³¹I group than in the control group. In the investigated groups, the tail DNA values were significantly different between non-smokers and past or current smokers, but excess PCC fragments did not significantly differ by smoking status. It is important to measure exposure to low doses of ionizing radiation and assess the potential risk from this exposure. Such investigations support the need to continue epidemiological and experimental studies to improve our understanding of the mechanisms of the health effects of radionuclides and to develop predictive models of the behavior of these complex systems in response to low-dose radiation.

Redox-related biomarkers in physical exercise

Research in redox biology of exercise has made considerable advances in the last 70 years. Since the seminal study of George Pake's group calculating the content of free radicals in skeletal muscle in resting conditions in 1954, many discoveries have been made in the field. The first section of this review is devoted to highlight the main research findings and fundamental changes in the exercise redox biology discipline. It includes: i) the first steps in free radical research, ii) the relation between exercise and oxidative damage, iii) the redox regulation of muscle fatigue, iv) the sources of free radicals during muscle contractions, and v) the role of reactive oxygen species as regulators of gene transcription and adaptations in skeletal muscle.

In the second section of the manuscript, we review the available biomarkers for assessing health, performance, recovery during exercise training and overtraining in the sport population. Among the set of biomarkers that could be determined in exercise studies we deepen on the four categories of redox biomarkers: i) oxidants, ii) antioxidants, iii) oxidation products (markers of oxidative damage), and iv) measurements of the redox balance (markers of oxidative stress). The main drawbacks, strengths, weaknesses, and methodological considerations of every biomarker are also discussed.

Traditional Indian sports - A case-control study on Kho Kho players investigating genomic instability and oxidative stress as a function of metabolic genotypes

The beneficial effects of physical exercise regularly for overall well being, or for recreational or professional purposes are widely accepted in clinical practice and have from time immemorial been the reasons for performing traditional sports. On the contrary, there is also evidence implying increased oxidative stress and genetic damage from intensive exercising. Depending on the intensity, time, frequency and characteristics of exercises, there can be differential induction of oxidative stress and provocation of oxidation of cellular macromolecules (including DNA) and cellular dysfunction which can likely accumulate with age, physical attributes and increase the susceptibility to disease on one hand, while stimulating cell signalling pathways leading to cell adaptation and improved resistance to stress, on the other. In order to observe if continuous sports activities as in Kho Kho increase oxidation capacity, which can also provoke oxidation of cellular macromolecules, the effects on oxidative/antioxidant changes and DNA damage in professional Kho Kho players modulated by individual genetic differences were assessed. Kho Kho, a traditional Indian game of ‘Tag’, is an all-time favourite which requires endurance, agility and strength. Healthy Kho Kho players (20.27 ± 0.28 y; sports age 6.78 ± 0.52 y) and controls (20.90 ± 0.45 y) were matched for age, gender, BMI, VO₂ max (maximal oxygen uptake), frequency of GSTT1 (present/null), M1 (present/null), SOD2 (C199T) polymorphisms but differed for variant allele frequencies of GSTP1 (A313G) and SOD2 (C47T). Players compared to controls had significantly increased levels of DNA damage (1.8x, 44.66 ± 1.68 vs. 23.85 ± 1.79 μm, p = 0.000), lipid (MDA) peroxidation (2x, 1.72 ± 0.06 vs. 0.83 ± 0.16 μmol/l, p = 0.000) and total antioxidant capacity (1.09x, 1.69 ± 0.06 vs. 1.11 ± 0.03 mmol Trolox equivalent/l, p = 0.000) but with no differences for SOD activity (94.99 ± 2.42 vs. 93.36 ± 2.54 U/ml, p = 0.935). These results suggest that the players have increased genetic damage and oxidative stress probably from the intense physical activity in the absence of other exposure(s) as other attributes were comparable in the study group. The players may therefore be at increased risk for susceptibility to cancer, various diseases and precocious age-related changes and should be sensitized to health risks related to regular intensive physical exercise.