Vol 98, No 4 (2021)

The purpose of the study — to identify the factors contributing to the spread of the novel coronavirus infection within the territory of the Republic of Moldova and to develop measures aimed at their elimination.

Materials and methods. In May 2020, experts of Rospotrebnadzor (the Federal Service for Surveillance on Consumer Rights Protection and Human Wellbeing), together with leading employees of institutions participating in planning and implementing measures aimed at prevention of COVID-19 spread, conducted a detailed analysis of epidemic control and curative measures in 10 healthcare organizations in the Republic of Moldova. They assessed the effectiveness of the undertaken actions in in-patient facilities, in laboratories, and in the country in general.

Results. The existing approaches to treatment of patients with COVID-19 and to laboratory diagnostics were in line with the common practices; the adequacy of measures was evidenced by the hospital bed capacity and the stock of artificial lung ventilation machines. In the meantime, the experts came across the factors that obviously contributed to the infection spread. Their elimination could intercept some paths of infection and improve the situation.

Conclusion. The analysis of the current measures and their results is important for planning and implementing actions aimed at improvement of the epidemic situation in different regions. The collaborative efforts helped slow down the outbreak in the Bender psychoneurological residential facility; outbreaks were prevented in other limited-access institutions; the incidence among healthcare workers decreased; the daily number of new COVID-19 cases decreased to 0–5 during the summer months in the Dniestrian Moldovan Republic. Presently, there is a clear picture of approaches that should be taken to decrease the incidence. Most likely, the experience obtained in the fight against the novel coronavirus infection will be of great use in future if any new variants of viruses emerge.

Introduction. COVID-19 has become a global impediment by bringing everything to a halt starting from January 2020. India underwent the lockdown starting from 22nd March 2020 with the sudden spike in the number of COVID-19 patients in major cities and states. This study focused on how metabolites play a crucial role in SARSCoV-2 prognosis.

Materials and methods. Metabolome profiling of 106 plasma samples and 24 swab samples from symptomatic patients in the Indian population of the Mumbai region was done. COVID-19 positive samples were further segregated under the non-severe COVID-19 and severe COVID-19 patient cohort for both plasma and swab.

Results. After analyzing the raw files, total 7,949 and 12,871 metabolites in plasma and swab were found. 11 and 35 significantly altered metabolites were found in COVID-19 positive compared to COVID-19 negative plasma and swab samples, respectively. Also, 9 and 23 significantly altered metabolites were found in severe COVID-19 positive to non-severe COVID-19 positive plasma and swab samples, respectively. The majorly affected pathways in COVID-19 patients were found to be the amino acid metabolism pathway, sphingosine metabolism pathway, and bile salt metabolism pathway.

Conclusion. This study facilitates identification of potential metabolite-based biomarker candidates for rapid diagnosis and prognosis for clinical applications.

Introduction. The productivity of microbial synthesis of stable nanoparticles is determined by the growth stage of the populations of bacterial cultures used to obtain nanostructures. The study of the biocidal activity of biogenic nanoparticles of cadmium sulfide (NPsCdS), comparable in properties with nanomaterials obtained by physicochemical methods, is promising.

The aim of this work was to evaluate the effect of the cell growth phase of the bacterial strains Bacillus subtilis 168 and Shewanella oneidensis MR-1 on the efficiency of biosynthesis of NPsCdS and to study their bactericidal properties against a number of gram-positive and gram-negative strains of microorganisms.

Material and methods. Nanoparticles were obtained by introducing Na₂S and CdCl₂ salts to a final concentration of 2 mM : 2 mM in liquid bacterial cultures with cells in different phases of growth. The efficiency of NPsCdS biosynthesis was evaluated by the optical density of aqueous nanoparticles solutions. The bactericidal properties of NPsCdS were determined by the diameter of zone of inhibition growth of gram-positive bacteria B. subtilis 168, B. amyloliquefaciens, Streptococcus salivarius, Rhodococcus rhodochrous and gram-negative S. oneidensis MR-1, Escherichia coli K-12, Pseudomonas putida.

Results. It was found that the use of cells in the stationary phase of growth (18–24 hours) contributes to obtaining the maximum amount of NPsCdS corresponding to concentrations of 1.0–1.2 mg/ml. The high antimicrobial activity of NPsCdS was shown against gram-positive microorganisms, among gram-negative bacteria, P. putida strain showed insignificant sensitivity.

Discussion. The experimental results expand scientific data about the effect of the phase of bacterial growth cycle on biosynthesis of nanoparticles. The stationary phase of growth of B. subtilis 168, S. oneidensis MR-1 is optimal for obtaining of NPsCdS. For the first time, the cytotoxicity of NPsCdS/Shewanella against bacteria of various taxonomic groups was demonstrated.

Conclusion. An effective method for obtaining extracellular NPsCdS using bacteria B. subtilis 168, S. oneidensis MR-1 in the stationary phase of growth has been developed. The biocidal activity of biogenic NPsCdS was shown, which allows to consider them as a new class of antimicrobial agents.

Rationale. Countries of Africa, especially countries in sub-Saharan Africa, represent a region characterized by high incidence of chronic hepatitis B virus (HBV) and hepatitis C virus (HCV) infections. Methods for detection of HBV and HCV in low and middle-income countries differ from those that are used in countries having access to high-cost technologies. The Republic of Guinea is a region with high prevalence of hepatotropic viruses, however, the information on HBV and HCV prevalence in the area is extremely limited, thus emphasizing the significance of this study.

The purpose of the study is to evaluate the need for improving laboratory diagnostics of parenteral HBV and HCV infections in the Republic of Guinea.

Materials and methods. A total of 2,616 samples of blood serum were tested, the samples were collected from apparently healthy residents of the Republic of Guinea during the routine medical checkup. The testing included qualitative detection of HBsAg, anti-HBs IgG, anti-HBcore IgG, anti-HCV IgG antibodies as well as HBV DNA and HCV RNA.

Results. The detection frequency of serological markers of HBV and HCV infections was 80.77% and 18%, respectively. However, HBsAg was detected only in 16.01% of individuals. Tests for detection of HBV DNA were performed among seropositive patients and patients seronegative by other HBV markers, HBV DNA was detected in 22.36% of cases, including 6.07% of HBsAg-negative cases. HCV RNA was detected in 2.2% of cases. Both HCV RNA and HBV DNA were detected in 27 people, including 19 HBsAg-negative cases, thus accounting for 1.03% of the examined group.

Conclusions. The markers that are currently used for laboratory detection of HBV and HCV in the Republic of Guinea are not efficient enough to diagnose reliably all cases. Undoubtedly, there is an urgent need to improve laboratory diagnostics for timely detection of parenteral viral hepatitis. Routine laboratory operations need assays for additional serological and molecular markers of HCV and HBV infections.

The review considers the nature of clinical and pathological disorders caused by highly pathogenic coronaviruses in the human body, analyzes the causes of systemic damage to various organs and tissues, the strategy of virus reproduction and the associated syndrome of cytokine reactivity with the development of specific immunodeficiency at the molecular level. The most developed approaches to the targeted therapy of cytokine reactivity syndrome and SARS including elements of theranostics — monitoring of molecular targets for targeted therapy — are described. An example of an innovative bioengineering technology associated with the reprogramming of cells of the primary "echelon of defense" with the ability to endow them with highly specific skills of directed destruction of cells infected with a virus is given.

The aim of the study — demonstration of the capabilities of new generation geographic information system software and agent-based modeling for solving epidemiological problems (on the example of the spread of measles in a metropolis).

Materials and methods. Examples of the use of thematic layers and the functionality of the geoinformation platform, as well as the developed multi-agent model of measles spread in the megalopolis, are given. The measles spread model is presented as following three independent sub-models or nested models: behavior model, infection model, infectious process model. The modularity and independence of the sub-models allow the use

of the necessary statistical and clinical data, both directly related to the studied disease and demographic indicators, which are analyzed and stored in the thematic layers of the platform.

Results. The developed software tools allow visualizing, analyzing and short-term forecasting of the spread of the disease in the study area, with the ability to generate reports, which can be a useful and relevant addition to the daily work of specialists, contribute to the improvement and deepening of practical skills and abilities, in accordance with the types and tasks of professional activities, as well as expand opportunities for assistance in management decision making.

The objective is to perform a comparative evaluation of the pancreatic hydrolysates prepared from fish and squid to determine the optimal culture medium for Listeria monocytogenes.

Materials and methods. The following raw materials were used in the study: Pacific Herring (Clupea pallasii), Alaska Pollock (Gadus chalcogrammus), Common Roach (Rutilus rutilus lacustris), European Squid (Loligo vulgaris). The raw materials were subjected to enzymatic hydrolysis using the pancreas (according to Hottinger). A study of the physicochemical properties of pancreatic hydrolysates (content of free amino nitrogen (FAN), acidity of fish hydrolysates, the amino acid composition) was carried out.. The specific activity of nutrient media during the cultivation of the test strain L. monocytogenes 766 was assessed by a complex of microbiological methods.

Results and discussion. The highest content of FAN at the end of enzymatic hydrolysis was observed in the pancreatic hydrolysate of the common roach (6%), the acidity of the hydrolysate remained stable from 6th to 13^th day of the hydrolysis process (pH 7.2). Pancreatic hydrolysate of the common roach contained a number of amino acids that are most essential for the growth of Listeria. An assessment of the biological properties of nutrient media prepared on the basis of the obtained hydrolysates demonstrated that the best results in terms of sensitivity and germination of L. monocytogenes 766 showed a nutrient medium based on the pancreatic hydrolysate of the common roach. During the cultivation of L. monocytogenes 766 the test strain retained its morphological and cultural properties and did not show signs of dissociation.

Conclusion. The research results have shown that the pancreatic hydrolysate of the common roach is a promising protein basis for the construction of an experimental environment for listeria.

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