Introduction and purpose: Fibromyalgia is a chronic condition affecting almost 2% of the general population, mostly women. The main symptoms are chronic diffuse musculoskeletal pain or stiffness, tiredness, nonrestorative sleep, anxiety, depression and cognitive dysfunction. The etiology of fibromyalgia remains unclear and has been the subject of debate and scientific investigation. The aim of this article was to collect and analyse current and new information on the etiology of fibromyalgia and present the most popular hypotheses. Brief description of the state of knowledge: Pathogenesis of fibromyalgia is multifactorial. Genetic factors, in addition to environmental factors, such as psychical stress and various types of infection, are considered to be the triggers of the disease. Central sensitization became a commonly accepted hypothesis of the fibromyalgia's pathogenesis. However, the newest finding of small fiber neuropathy in patients with fibromyalgia supports another hypothesis, in which the disease is presented as stress-related dysautonomia with neuropathic pain features. Conclusions: Understanding the pathogenesis of fibromyalgia is essential to provide the best care to the patients with fibromyalgia. Although there are multiple evidence for central sensitization hypothesis, new findings continue to emerge and question commonly accepted paradigm. Despite numerous findings on etiology of fibromyalgia, more studies are needed.

AIM OF THE STUDY. The study aims to present the current state of knowledge on the impact of traditional cigarettes and the nicotine contained in them on the incidence and course of SARS-CoV-2 infection. Moreover, we decided to exhibit the possibility of using this substance to treat COVID-19 infections. MATERIAL AND METHODS. The latest available scientific publications were reviewed until November 14, 2020, from the PubMed platform. RESULTS. Nicotine is a cholinergic agonist and pro-inflammatory cytokines inhibitor. Some authors present that smoking and nicotine reduce the amount of the ACE2 receptors which are used by the novel coronavirus to enter cells, while others claim that ACE2 receptors are upregulated in smokers. Moreover, the interaction of SARS-CoV-2 with nAChR is suspected of dysregulation of the nicotinic cholinergic system, which is associated with the pathophysiology of COVID-19. Due to the harmfulness of cigarettes, a high frequency of smokers is suspected among people suffering from COVID-19. However, some studies report that the number of current smokers hospitalized for SARS-CoV-2 infection is lower than expected, considering the prevalence of smoking in individual countries. Nicotine could restore the impaired function of the nicotine cholinergic system and possibly mitigate the cytokine storm. CONCLUSIONS. There is no clear attitude regarding the impact of smoking on the new coronavirus infection now. Researchers do not recommend smoking as a tool to combat the pandemic and show the importance of fighting addiction to reduce the adverse health effects of smoking. Both the relationship between cigarettes and the morbidity and severity of COVID-19, as well as the possibility of using nicotine in the treatment of the disease, require further analysis.

Objective: Triclosan is an aromatic organic compound with antibacterial and fungicidal properties, most often used in soaps, toothpaste and other cosmetics. The study aimed to analyze the influence of triclosan on the female and male reproductive systems and the consequences on fertility. Materials and methods: A review of the latest literature derived from PubMed and Google Scholar platforms has been made. After following the search strategy, applying inclusion criteria and analysis of the obtained results assessed by two independent analysts, 45 studies were included in the review. Results: Due to the similar structure of triclosan (TCS) to anthropogenic estrogens, TCS can interact with hormone receptors, affect hormone balance, and influence reproductive health and carcinogenesis. It has been noted that TCS might affect luteal cell progesterone production and disrupt ovarian function. Prenatal exposure to the chemical can have an impact on the reproductive system of newborns. TCS might be a risk factor for endometrial physiology and impair reproduction. TCS negatively affects the male reproductive system via interrupting steroidogenesis mediated miRNA (micro-ribonucleic acid) pathways. Negative effects of TCS on early development and embryogenesis in animals were evidenced. Moreover, TCS has the potential to promote carcinogenesis in human breast, ovarian, and prostate cells. Conclusion: Potential impact of TCS on the reproductive system raises concern about its safety, due to its similar structure to anthropogenic estrogens and detection in the environment. TCS-induced disruption of hormone levels in the female and male reproductive systems may be the cause of impaired reproductive health, resulting in subfertility. Further investigations are required to evaluate the mechanisms and effect of TCS on human reproductive health.

THE AIM OF THE STUDY. Is to present the state of knowledge from April and May 2020 about the influence of Bacillus-Calmette-Guérin vaccination against tuberculosis on incidence and mortality due to COVID-19. MATERIAL AND METHODS. A review of the latest literature till 9 May 2020 has been made. PubMed and ResearchGate databases and WHO reports were used. RESULTS. Immunomodulatory properties of the tuberculosis vaccine which protects against severe cases of tuberculosis and partly against other infections are indicated, including viral and respiratory infections. The BCG vaccine induces heterologous immunity and trained innate immunity. It was noted that in countries which maintain obligatory BCG vaccination COVID-19 incidence and mortality are lower than in countries that have stopped or never introduced BCG as mandatory vaccination. Most analysis confirmed this relationship, but they indicated the possible impact of other factors, such as genetics in the population, the type of strain from BCG vaccine, the level of health care and the wealth of a nation, the structure of migration, co-morbidities and a policy of introducing social distance. CONCLUSIONS. At the moment, we do not have enough evidence to support or deny the hypothesis of COVID-19 reduction in incidence and mortality in countries maintaining obligatory BCG vaccination. Other factors that might affect the results should be considered in further analysis. The results of clinical trials will provide more reliable proofs than analysis of epidemiological data. WHO does not recommend BCG vaccination to prevent COVID-19 and recommends it to newborns from areas with a higher incidence of tuberculosis.

Spirulina is a microalga that presents various important pro-health properties, for instance lowering blood pressure in the research. The study aims to appraise the efficacy of Spirulina administration on systolic (SBP) and diastolic blood pressure (DBP). Randomized controlled trials (RCTs) were retrieved by a systematic search of PubMed, Web of Science, and the Cochrane Library databases from inception to June 2021 according to a standardized protocol. The effect size of each study was counted from mean and standard deviation before and after the intervention and shown as Un-standardized mean difference and 95% confidence interval. Sensitivity analyses were performed. Meta-analysis on 5 RCTs with 230 subjects was eligible. The amount of Spirulina ranged from 1 to 8 g per day, and intervention durations ranged from 2 to 12 weeks. Data analysis indicated that Spirulina supplementation led to a significant lowering of SBP (Mean Difference (MD): −4.59 mmHg, 95% Confidence Interval (CI): −8.20 to −0.99, I square statistic (I2) = 65%) and significant lowering of DBP (MD: −7.02 mmHg, CI: −8.86 to −5.18, I2 = 11%), particularly in a subgroup of hypertensive patients. Spirulina administration might have a supportive effect on the prevention and treatment of hypertension. More exact randomized controlled trials are needed to clarify the effect of Spirulina supplementation on blood pressure.