Galina V. Zhukova

A new personalized approach is proposed to predict the professional suitability of railway transport workers under the influence of stressful factors, based on the study of the effect of salivary fluid of subjects before and after a work shift on the intensity of the glow of the bioenzyme reaction of luminous bacteria: NADH:FMN-oxidoreductase+luciferase. The integral method, which signals the magnitude of the stress effect, is based on changes in saliva components such as lactate, ions and cations, as well as nitrate and sulfate chlorides under the influence of stress. This made it possible to identify, using the example of Russian Railways dispatchers, a risk group and a group of stress-resistant workers, which is important to reduce accidents at Russian Railways. The conditions that reduce the stressful workload necessary for the development of effective measures for the prevention of stressful situations and the preservation of workers’ ability to work have been identified.

A new personalized approach is proposed to predict the professional suitability of railway transport workers under the influence of stressful factors, based on the study of the effect of salivary fluid of subjects before and after a work shift on the intensity of the glow of the coupled enzyme reaction of luminous bacteria: NADH:FMN-oxidoreductase + luciferase. The integral method, which signals the magnitude of the stress effect, is based on changes in saliva components such as lactate, ions and cations, as well as nitrate and sulfate chlorides under the influence of stress. This made it possible to identify, using the example of Russian Railways dispatchers, a risk group, and a group of stress-resistant workers, which is important to reduce accidents at Russian Railways. The conditions that reduce the stressful workload necessary for the development of effective measures for the prevention of stressful situations and the preservation of workers’ ability to work have been identified.

Saliva is one of the most significant biological liquids for the development of a simple, rapid, and non-invasive biosensor for training load diagnostics. There is an opinion that enzymatic bioassays are more relevant in terms of biology. The present paper is aimed at investigating the effects of saliva samples, upon altering the lactate content, on the activity of a multi-enzyme, namely lactate dehydrogenase + NAD(P)H:FMN-oxidoreductase + luciferase (LDH + Red + Luc). Optimal enzymes and their substrate composition of the proposed multi-enzyme system were chosen. During the tests of the lactate dependence, the enzymatic bioassay showed good linearity to lactate in the range from 0.05 mM to 0.25 mM. The activity of the LDH + Red + Luc enzyme system was tested in the presence of 20 saliva samples taken from students whose lactate levels were compared by the Barker and Summerson colorimetric method. The results showed a good correlation. The proposed LDH + Red + Luc enzyme system could be a useful, competitive, and non-invasive tool for correct and rapid monitoring of lactate in saliva. This enzyme-based bioassay is easy to use, rapid, and has the potential to deliver point-of-care diagnostics in a cost-effective manner.

The paper considers the creation of a diagnostic system based on morphological and biophysical indicators that allows us to understand the influence of the climatic component, as well as stress factors on the general physiological state of young people for further correction of preventive measures and preservation of the health of the peoples of the Far North. The aim of the study is a comprehensive assessment of the health of young people living in the Far North based on the results of bioluminescent saliva activity, stress-emotional state obtained before and after intense mental stress, as well as anthropometric and bioimpedance indicators. 117 students of the Medical Institute of Surgut State University took part in the survey at a young age (18-23 years) during the educational process (rest) and during the examination session (mental load) in the first half of the year of study (autumn-winter 2021). The stress-emotional state was assessed using the Spielberger-Khanin test, the functional state of students They were studied using bioluminescent salivary fluid testing, anthropometric and bioimpedance methods. Samples were obtained by spitting unstimulated saliva into a test tube. As a result of the study, regional features of the physique of young people were revealed, which indicates the formation of a phenotype adapted to living conditions in the northern region. The relationship between the stress-emotional status of adolescents and the level of inhibition of the bioluminescent enzymatic system by saliva samples taken before and after mental stress was shown. The value of the residual glow had an increased indicator for the state of rest and significantly reduced the intensity of the bioluminescent glow under mental stress. The methodological development obtained in the future will make it possible to effectively manage the methods and methods of diagnosing young people, taking into account the influence of external factors, climatic zones and conditions.

Th e aim of the research was to evaluate the possibilities of using saliva as an indicator of mental and physical stress in the bioluminescent method. Material and methods. Th e object of the study was the saliva of schoolchildren (15-16 years old, n=15), students (19-20 years old, Krasnoyarsk State Medical University and Surgut State University, n=227) and athletes (19-20 years old, n=25). Saliva sampling was performed before and aft er muscle tension and psycho-emotional stress. Th e bacterial bioenzyme system NADH:FMN-oxidoreductase + luciferase was used as a test system. Th e residual glow intensity was used as an integral indicator of body fatigue [1, 2]. Results. It shows the greatest fatigue of schoolchildren aft er mental stress and the least fatigue aft er physical exertion. Boys got tired aft er physical exertion, girls aft er mental exertion. Physical activity tired the excellent schoolchildren. Mental stress caused fatigue of the good schoolchildren. Th e fatigue of students during the study session was revealed, regardless of the region of residence and the component composition of saliva. Students had the same index of stress resistance regardless of the state of rest or mental stress. Indicators of situational and personal anxiety were higher among students from the northern regions. For the fi rst time, the least fatigue of highly qualifi ed athletes was shown during high-intensity physical activity, which distinguishes them from low-skilled athletes. Th e concentration of lactate in the saliva of athletes increased with fatigue. Conclusion. Mental and physical overload aff ect schoolchildren regardless of their academic performance and length of study. Psychological or emotional stress causes fatigue of the students’ body, regardless of the component composition of their saliva and the region of residence. Physical (muscular) tension of varying intensity tires the body of highly qualifi ed athletes to a lesser extent, which makes it possible to reveal their high stress resistance to overloads. Th us, saliva can serve as an indicator of mental and physical stress in the bioluminescent method. It is planned to develop new express methods for pre-trip inspections of railway employees.

Upcoming professional sports authorities seek rapid noninvasive biosensing tools for regular monitoring of athletes' physiological states. The analysis of saliva through luminescence‐based biosensors has been perceived as a suitable candidate for such purposes. The present study reports a qualitative bioluminescence assay based on a coupled enzyme system that consists of bacterial luciferase (BLuc) and nicotinamide adenine dinucleotide (NADH):flavin mononucleotide (FMN) oxidoreductase (Red), BLuc‐Red, for the express diagnostics of athletes' stress levels before and after physical exertion. The volunteers who participated in the study were grouped as freestyle wrestlers and students who adapted to different levels of physical activities. Under physical exertion modelling conditions, the influence of participant saliva on BLuc‐Red catalyzed light emission was investigated. Results showed a significant increase in residual luminescence (I_exp, mean maximum bioluminescence intensity of the experimental measurement (I_exp); I_c, luminescence intensity in control; I_exp/I_c, %) values for participants in the wrestler group while a decrease in the student group (P < 0.05). Such contrasting residual luminescence values in both groups were found to be dependent on the catalase activity of saliva. The proposed bioluminescence assay can be utilized as a potential nonspecific biosensing tool for determining the physical state of athletes under high loads.