Context: Increased oxidative stress is a significant part of pathogenesis of smoking-related cancer. Aim: The study aims to investigate changes in antioxidant status induced by chronic cigarette smoking in cancer patients and healthy subjects. Setting and Design: We examined the venous blood samples of 54 healthy subjects, both smokers (25) and non-smokers and of 50 patients with smoking-related cancer, both smokers (34) and non-smokers. Materials and Methods: We measured the activities of five antioxidant (AO) enzymes: glutathione peroxidase, glutathione transferase (GST), glutathione reductase, superoxide dismutase and catalase in the blood of 50 cancer patients and 54 healthy persons. Damage to cellular structures (level of malonic dialdehyde, micro viscosity of erythrocyte membranes, number of leukocyte DNA breaks) was determined. Statistical analysis of results obtained was performed using conventional and multi-factorial statistical methods. Results: Statistically significant increase in GST activity and DNA breaks, but decrease of membranes micro viscosity in cancer patients, compared with healthy subjects were obtained. In the cancer patients, no influence of smoking on studied parameters was found. Correlations of parameters within cancer patients and healthy subjects group did not coincide with each other. Conclusions: Changes of AO status parameters and oxidative damages in cell structures are related to tumor processes indicating the augmentation of oxidative stress in human blood. This study demonstrated potential applicability of a statistical model based on the evaluated biomarkers of oxidative stress to determine a smoking-induced harm of cancer incidence in healthy subjects.

This paper introduces the reader to the field of liquid biopsies and cell-free nucleic acids, focusing on circulating tumor DNA (ctDNA) in breast cancer (BC). BC is the most common type of cancer in women, and progress with regard to treatment has been made in recent years. Despite this, there remain a number of unresolved issues in the treatment of BC; in particular, early detection and diagnosis, reliable markers of response to treatment and for the prediction of recurrence and metastasis, especially for unfavorable subtypes, are needed. It is also important to identify biomarkers for the assessment of drug resistance and for disease monitoring. Our work is devoted to ctDNA, which may be such a marker. Here, we describe its main characteristics and potential applications in clinical oncology. This review considers the results of studies devoted to the analysis of the prognostic and predictive roles of various methods for the determination of ctDNA in BC patients. Currently known epigenetic changes in ctDNA with clinical significance are reviewed. The possibility of using ctDNA as a predictive and prognostic marker for monitoring BC and predicting the recurrence and metastasis of cancer is also discussed, which may become an important part of a precision approach to the treatment of BC.

Intensive space exploration includes profound investigations on the effect of weightlessness and cosmic radiation on plant growth and development. Tomato seeds are often used in such experiments though up to date the results have given rather vague information about biochemical changes in mature plants grown from seeds subjected to spaceflight. The effect of half a year of storage in the International Space Station (ISS) on tomato seeds (cultivar Podmoskovny ranny) was studied by analyzing the biochemical characteristics and mineral content of mature plants grown from these seeds both in greenhouse and field conditions. A significant increase was recorded in ascorbic acid, polyphenol and carotenoid contents, and total antioxidant activity (AOA), with higher changes in the field conditions compared to greenhouse. Contrary to control plants, the ones derived from space-stored seeds demonstrated a significant decrease in root AOA. The latter plants also showed a higher yield, but lower content of fruit dry matter, sugars, total dissolved solids and organic acids. The fruits of plants derived from space-stored seeds demonstrated decreased levels of Fe, Cu and taste index. The described results reflect the existence of oxidative stress in mature tomato plants as a long-term consequence of the effect of spaceflight on seed quality, whereas the higher yield may be attributed to genetic modifications.

This review covers the stages of studying left-helical Z-DNA form, from its discovery in 1979 until the present time. The repetitive nucleotide sequences that are capable of the B–Z...