Том 2, № 2 (2022)

Objective. Scientific substantiation of preventive measures aimed at minimizing the deleterious effects of stress factors requires the study of the processes of free-radical oxidation of biomolecules from the position of physiological mechanisms of stress-response development in the animal organism. The aim of the study was to investigate and correlate the indicators of pro- and antioxidant systems and the level of blood stress hormones (ACTH and cortisol) in cattle of different ages (1-, 3-, 6-, 9- and 12-month-old black-breed heifers) for correction of housing and operating conditions. Materials and methods. Scientific research was carried out on the basis of CJSC "Rassvet", Lyubinsky district, Omsk region, on five groups of clinically healthy black-breed heifers of 10 heads each, at the age of 1-, 3-, 6-, 9- and 12-months with similar body weight indices. The concentration of superoxide dismutase (SOD) of blood erythrocytes was determined by colorimetric method, glutathione reductase - by kinetic method using commercial reagents of "Randox" company (England) on automatic biochemical analyzer "Autolab" AMS PM4000 (manufacturer "LIVIA" Italy). The concentration of reduced glutathione of blood erythrocytes was determined by the reaction of glutathione with excess alloxan. The amount of malonic dialdehyde was determined by reaction with thiobarbituric acid. Quantitative determination of ACTH and cortisol levels in blood serum was carried out by solid-phase enzyme immunoassay (Biomerica ELISA test, USA) on an immunoenzyme analyzer "Elisys Quattro" (manufacturer Human GmbH Germany). Results. The study did not reveal an increase in the level of key stress hormones, although it can be noted that there is a tendency to a wave-like change in the level of ACTH. The concentration of serum cortisol of 1-, 3-, 6-, and 9-month-old heifers is approximately the same, increasing by the 12th month of postnatal life. The intensity of free-radical oxidation, estimated by the content of malonic dialdehyde in the studied age groups of animals is at the same level from the 1st to the 9th months. The concentration of glutathione (non-enzymatic link of antioxidant system) in erythrocytes of blood in 1- and 6-month-old animals is higher than in 3-, 9- and 12-month-old animals, the main indicators of the enzymatic link of antioxidant system - glutathione reductase and superoxide dismutase are at approximately the same level in the age range from the 1st to the 12th month. Conclusion. The obtained data indicate that the most vulnerable period for the action of stress factors is 3 and 6 months of age, when animals are transferred to new housing conditions, and up to 3 months of age the low level of free-radical oxidation is maintained mainly due to an increase in the concentration of glutathione reductase in the blood, and from 6 months of age a significant contribution is made by glutathione. For the first time the comparison of the indicators of antioxidant status of blood of cattle of different ages with the level of stress hormones (ACTH and cortisol) was carried out.

This literature review provides a general overview of oxidative stress. The peculiarities of the influence of reactive oxygen species and lipid peroxidation processes on metabolism during physical activity have been revealed. An analysis of literary sources was carried out in order to clarify the characteristics of the course of oxidative stress during physical activity. Antioxidant defenses of the body have been described that can prevent damage caused by oxidative stress. Oxidative stress is accompanied by the generation of reactive oxygen species that damage various structural elements of the cell and its membrane. The state of the antioxidant system during physical activity depends on its duration, power and intensity, and the type of sport. With moderate physical activity, compensatory neutralization of reactive oxygen species occurs. Intense physical activity reduces the antioxidant reserve in the body and contributes to the pronounced manifestation of oxidative stress. These facts have been proven both for experimental animals and for humans. In this case, there is a direct need to introduce foods enriched with antioxidants into the diet or use dietary supplements with antioxidant properties.

Today the issue of prevention of "emotional burnout" of medical workers has acquired great importance in connection with the epidemic of new coronavirus infection COVID-19. The COVID-19 pandemic has further complicated the existing problem of overburdened health care systems, thereby increasing the impact of emotional burnout. The unfavorable psychological effects affecting health care workers have increased significantly. This has been seen before, in care settings with severe infectious diseases, with depression, alcohol abuse and sleep disturbances in health care workers. In late 2019, a new coronavirus infection (COVID-19) attracted intense global attention. Due to its severe course, extreme epidemiologic risk, high mortality rate, and limited knowledge about COVID-19, healthcare workers are under extreme physical and psychological pressure in the line of duty. Not only are they at increased risk of infection, but they are also reported to experience depression, anxiety, insomnia and worry.  Moreover, fears shared by the families, friends and neighbors of health workers lead to disrupted interpersonal relationships, which may be another influencing factor causing mental illness among health workers. Mental health problems affect health workers' attention, understanding and decision-making ability, which can negatively affect their work. Thus, protecting the mental well-being of health workers is important for the epidemic and their own health. The overall mental health of nurses during the COVID-19 outbreak has been shown to be poor, and several exposure factors have been identified: working in high-risk wards, inadequate training, delayed diagnosis, inappropriate or lack of personal protective equipment (PPE), prolonged contact with COVID-19 patients, having children, changing daily priorities, social support, irregular working hours, separation from family and friends, and increased physical activity. In the face of a sudden disaster such as COVID-19, it is important to pay attention to the mental health of nursing staff. Measures such as recruitment of new nurses to reduce workload, WHO recommendations on use of PPE, correcting working hours and ensuring hours of effective rest should be adapted.