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Content available Adverse effects of antioxidative vitamins
High doses of synthetic antioxidative vitamins: A, E, C and β-carotene are often used on long-term basis in numerous preventive and therapeutic medical applications. Instead of expected health effects, the use of those vitamins may however lead to cases of hypervitaminosis and even to intoxication. The article points out main principles of safety which are to be observed during supplementation with antioxidative vitamins. Toxic effects resulting from erroneous administration of high doses of those substances on organs and systems of the organism are also discussed. Attention is drawn to interactions of antioxidative vitamins with concomitantly used drugs, as well as intensification of adverse effects caused by various exogenous chemical factors. Moreover, the article presents the evaluation of supplementation with these vitamins, which was performed in large studies.
Objectives The increasing number of devices emitting electromagnetic radiation (EMR) in people’s everyday life attracted the attention of researchers because of possible adverse effects of this factor on living organisms. One of the EMR effect may be peroxidation of lipid membranes formed as a result of free radical process. The article presents the results of in vitro studies aimed at identifying changes in malondialdehyde (MDA) concentration – a marker of lipid peroxidation and antioxidant role of vitamin A during the exposure of blood platelets to electromagnetic radiation generated by liquid-crystal-display (LCD) monitors. Material and Methods Electromagnetic radiation emitted by LCD monitors is characterized by parameters: 1 kHz frequency and 220 V/m intensity (15 cm from display screen). The time of exposure was 30 and 60 min. The study was conducted on porcine blood platelets. The samples were divided into 6 groups: unexposed to radiation, unexposed + vitamin A, exposed for 30 min, exposed for 30 min + vitamin A, exposed for 60 min, exposed for 60 min + vitamin A. Results The MDA concentration in blood platelets increases significantly as compared to control values after 60 min of exposure to EMR. A significant decrease in MDA concentration after the addition of vitamin A was noticed. In the blood samples exposed to EMR for 30 and 60 min the MDA concentration was significantly increased by addition of vitamin A. Conclusions The results show the possibly negative effect of electromagnetic radiation on the cellular membrane structure manifested by changes in malondialdehyde concentration and indicate a possible protective role of vitamin A in this process. Int J Occup Med Environ Health 2017;30(5):695–703
Content available remote The Antioxidative Barier in Patients with Colorectal Cancer
Colorectal cancer is still a major medical, economical and public health problem. Pathogenesis of colorectal cancer remains unknown. It is thought both genetic and environmental factors contribute to the etiology and progression of the disease. Reactive oxygen species are known to play a dual role in biological systems they can be either harmful or beneficial. Oxygen-free radicals are important mediators of damage to cell structures, including lipids, proteins and nucleic acids. Radical-related damage to cell structures has been proposed to play a key role in the development of many diseases including cancer.Humans have evolved complex antioxidant strategies to protect cells from oxidation.Total antioxidant capacity (TAC) considers the cumulative action of all the antioxidants present in plasma or other body fluids.The aim of the study was to investigate antioxidant status in patients with colorectal cancer measuring plasma TAC as a tool.Material and methods. The study group comprised 102 patients in different clinical stages operated on for colorectal cancer. To evaluate plasma total antioxidant capacity we used "Total Antioxidant Status Kit" - RandoxResults. Statistical evaluation of results demonstrated significantly lower serum total antioxidant capacity in patients with colorectal cancer, as compared to the healthy control group. We observed increase mean plasma total antioxidant capacity correlating with decrease of clinical disease stage.Conclusions. Colorectal patient have impairment antioxidant barrier. The deterioration of its functioning corresponds with the stage of the disease.
Content available remote Oxidative protein damage in patients with colorectal cancer
Colorectal cancer is a major public health concern particularly in developed countries. Despite decades of advances in the treatment and prevention of colorectal cancer, it remains the second most common cause of cancer death. There now exists convincing evidence that reactive oxygen species play an important role in the etiology and progression of a number of human diseases including colorectal cancer. Reactive oxygen species may damage all types of biological molecules. However, proteins are possibly the most immediate vehicle for inflicting oxidative damage on cells since they are often catalysts rather than stoichiometric mediators, hence, the effect of damage to one molecule is greater than stoi-chiometric.The aim of the study was to investigate oxidative protein damage in patients with colorectal cancer and its correlation with the clinical stage of the disease.Material and methods. The study group comprised 102 patients operated on for colorectal cancer in different clinical stages of the disease. Plasma carbonyl levels were determined using Levin's method.Results. Patients in all tumor groups showed significantly higher levels of plasma carbonyls when compared to healthy people. We observed an increase in mean plasma carbonyl levels correlating with an increase in the degree of disease advancement.Conclusions. This study demonstrates that reactive oxygen species may have a role in pathogenesis of colorectal cancer. The outcomes of this research seem to confirm that antioxidants may play a role in chemoprevention of colorectal cancer.
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