Ekologiya cheloveka (Human Ecology)

This article presents an algorithm for constructing and applying directed acyclic graphs (DAGs) in the planning of epidemiological and biomedical studies. DAGs are graphical tools for modeling complex relationships between variables, which is particularly relevant in biomedical science, where accurate assessment of causal relationships requires accounting for potential confounding factors. The importance of DAGs is emphasized for conceptualizing scientific hypotheses and understanding the structure of relationships between factors based on scientific data review and findings from previous studies. The use of DAGs enhances the quality of both study design and data analysis, providing a more grounded approach to selecting variables for inclusion in statistical models. DAGs make it possible to determine the minimal and sufficient set of factors for adjustment, with consideration of the roles of variables (confounders, mediators, colliders) in relation to the exposure (a probable risk factor) and the outcome (a disease or condition), thus reducing the likelihood of analytical errors. The article highlights the practical application of DAGs using available software and provides specific examples of their use in biomedical research. Finally, recommendations are offered for integrating DAGs into biomedical research practice, which may contribute to the broader adoption of modern multivariate statistical methods, improved interpretability, and enhanced reproducibility of scientific findings.

BACKGROUND: Employment for individuals with disabilities serves not only as a means of rehabilitation and social integration but also represents a stress-inducing factor involving a combination of technogenic and socio-psychological influences. Given the specific self-perception of their status, persons with disabilities develop a dynamic system of adaptive-compensatory mechanisms in response to occupational load. Therefore, the study of labor adaptation processes should encompass not only psychosocial aspects, as emphasized in most scientific data, but also consider the functional state of the body’s regulatory systems.

AIM: To assess the possibility of predicting adaptation outcomes to occupational load in working-age men with disabilities.

METHODS: The study group consisted of 59 working-age men with disabilities. The participants underwent employment-based practice in specialized rehabilitation and habilitation centers. The assessment included the Rogers–Diamond method for socio-psychological adaptation, morphometric parameters (weight, height, vital lung capacity, blood pressure, heart rate), and cardiointervalography with analysis of wave-related parameters (SI, HF, LF, VLF, LF/HF).

RESULTS: A comparative over-time analysis of cardiointervalography wave parameters revealed a statistically significant increase in the LF/HF ratio (p <0.001), indicating increased strain on adaptive mechanisms and a shift in autonomic tone toward sympathetic dominance. However, the increase in the VLF% index (p=0.045), recorded during further analysis, indicated the involvement of suprasegmental regulation of visceral functions. No significant changes were observed in socio-psychological adaptation. Morphometric parameters were assessed in relation to a composite index of regulatory system strain, determined after occupational load based on cardiointervalography data. ROC curve analysis was used to identify critical threshold values for age and body mass index in individuals with disabilities. Accordingly, these parameters can be regarded as predictors of unfavorable regulatory system responses to occupational exposure. Thus, if a person with a disability is employed at the age of 35 years or older, there is an 80% probability (p=0.005) of developing strain on adaptive mechanisms mechanisms as a response to occupational exposure. A similar correlation was identified with respect to body mass index: if, upon employment, the BMI is equal to or exceeds 26, there is an 80% probability (p=0.004) that an employed individual with a disability will develop autonomic imbalance.

CONCLUSION: The study identified specific features of adaptive responses to occupational load in working-age men with disabilities. The obtained data can be used to predict strain on the regulatory systems of internal organs in response to occupational exposure, as well as, from a practical standpoint, to design an effective work-rest schedule, weekly work timetable, and to determine the appropriate level of occupational load. A comprehensive biopsychosocial approach is required for a thorough evaluation of adaptive mechanisms, ensuring that employment serves a rehabilitative role for individuals with disabilities and delivers cost-effective results for employers.

BACKGROUND: Active development of nanotechnology and the use of research in many industries, including agriculture and medicine, require a comprehensive study of the influence of ultra dispersed substances on humans and animals. Today, we have limited evidence of the influence of nanoparticles on the microelement levels in organs and tissues. However, given the growing production and release of nanoparticles into the environment in processes, it is required to consider both the direct and indirect effects of particles of various chemical origin.

AIM: To evaluate the influence of copper, cobalt, and copper oxide nanoparticles on behavior and microelement levels in the liver, kidneys, and reproductive system in laboratory animals and to study their bioaccumulative potential upon intragastric administration.

METHODS: The experiment was conducted on male ICR mice divided into four variable groups of 6 subjects each, who were administered distilled water (control group) or 0.02 mg/kg suspensions of copper, cobalt, and copper oxide nanoparticles intragastrically for 20 days, once a day. We assessed the changes in body weight and anxiety in animals (the number of upright postures with and without support and the number of short-term grooming). At the end of the experiment, the animals were euthanized to sample the liver, kidneys, and reproductive organs and to determine the microelement levels using energy dispersive X-ray fluorescence.

RESULTS: After administration of all tested nanoparticles, the animals showed signs of anxiety, including an increased number of upright postures with support (the cobalt nanoparticle group) and a decreased number of upright postures without support accompanied by increased number of grooming acts (the copper and copper oxide nanoparticle groups). Animals of the same groups (copper and copper oxide) showed a decrease in body weight compared to the control group. An analysis of the microelement level in the liver, kidneys, and reproductive system revealed ambiguous changes in potassium, calcium, and sulfur levels and increased oxygen content in the testes and appendages. We detected no signs of bioaccumulation of copper, copper oxide, and cobalt nanoparticles in the studied organs. Thus, nanoparticles have indirect toxicity, which is manifested by changes in the microelement levels in organs and is characterized by the rapid elimination of nanoparticles.

CONCLUSION: Copper, cobalt, and copper oxide nanoparticles have a multidirectional indirect effect on the physiology and behavior of animals realized by changes in the microelement levels in their organs. We detected no accumulation of copper, cobalt, or copper oxide nanoparticles in the studied organs.

BACKGROUND: In recent decades, there has been an increased incidence of thyroid diseases worldwide. Following the Chernobyl accident, unique environmental and geochemical conditions developed in the Central Federal District, where the thyroid gland was affected by both environmental (microelemental deficiency, primarily iodine and selenium) and man-made (radioisotope contamination) factors. The studies have confirmed the relationship between iodine deficiency in the soil cover of the Central Federal District and the prevalence of thyroid diseases, including cancer. The study provides reliable data to prevent the diseases and to raise diagnostic alerts for the regional healthcare system and allows to develop the appropriate content for the population.

AIM: To analyze regional differences of thyroid disease incidence in the population of the Central Federal District based on its microelemental status.

METHODS: To analyze the population health of the Central Federal District and its constituent entities, we used population data, anonymized data on the number of patients with newly diagnosed thyroid diseases for 2013–2017, and incidence of malignant thyroid neoplasms for 1995–2023. To build a distribution model of microelements in the soil cover of the regions, the Unified State Register of Soil Resources was used. Each soil type–parent rock pair was assigned average content attributes. The reliability of microelemental estimates has been confirmed by field studies. We mapped iodine and selenium status of soils in the studied region. A nonparametric comparison of morbidity rates and map-based estimates was performed using the Spearman’s rank correlation.

RESULTS: An analysis of soil samples collected in 2007–2023 in some regions of the Central Federal District confirmed the correctness of the map-based model of the estimated microelemental composition of soil. We found significant negative correlations (R=-0.473; p=0.055) between the iodine levels in the soils of the Central Federal District and thyroid diseases. For the adult population, we found a positive correlation between radioisotope soil contamination and the incidence of thyroid cancer (R=0.711; p=0.001). In addition, for children (0–17 years), we found a negative correlation (R=-0.375; p=0.138) between the iodine level in soils and the incidence of thyroid cancer. As the selenium level in the soils of the Central Federal District is within the reference range, no relationship was found between the incidence and this microelement level in the soil (R=-0.091; p=0.729).

CONCLUSION: Comparison of geochemical and medical data in the context of spatial heterogeneity of risks associated with the effects of Chernobyl radioactive contamination of soil and natural deficiency confirmed the relationship between iodine deficiency in the environment and health status. There is a need to increase awareness of the population of the Central Federal District and heads of regional executive authorities of the adverse effects of micronutrient deficiency.